Both and in-between!
Sometimes I'm very very planned. I will have researched maps and tactics and will have coordinated a team. I will have pre-bought gear and items to help ensure success. It will have been set up days if not weeks in advance.
I will have regular sessions where the content will have been talked about but not planned so much.
I will have random ad-hoc sessions and I really enjoy PUGs.
I will have sessions where I *intend* to do whacky and wild things or very boring basic things to recharge from the batteries from the normal progression treadmill.
I'm sure Pantheon will make all things possible :)
"Best laid plans of mice and men."
I often have a clear idea of exactly what I want to do when I log on as I watch the clock tick down to the end of the work day. Typically, other than raids, those plans go out the window once I actually login. Either through X not being available or something shiny grabbing my attention I tend to end up doing something else.
I guess it depends. For the most part, I know exactly what I am going to do for the first part of the day, check out what's being sold and prepare for my wandering around of the game world, make sure i have enough food and water to get me by, and anything else i may need. After that, I go LFG and see where the world takes me.
But, that doesn't mean I never make plans. Plans do occur quite often, such as raiding, or trying to get some items for friends, I guess it depends on what needs done, but rarely does it change my beginninf routine's.
I'd say 70% of the time I have a broad strokes plan. Like "today I'm going to craft", or "this morning I"m going to that dungeon with my guildies".
I do this because of limited playtime, time zone, and conflicting schedules. If I don't plan things out in advance, I find myself constantly on my own in adventuring, because I log in hours later than many of my friends. (I had the opposite problem when I lived on the east coast, go figure). So I have gotten into the habit over time of letting them know what I want to do ahead of time, so that they'll a) wait for me and b) try to be available. When it comes to activities like crafting and gathering, I find that if I don't purposely set aside time to do those, I"m always busy helping someone with some adventuring thing, and thus I never progress.
That being said, I'll have at least a couple of days a weekw here I log in without a plan at all, on purpose. Being unstructured is what allows me to go out and help people (instead of always just working on my own priorities) and also gives me the opportunity to meet new people or try new things, because I'm not focused on something I had already planned to do.
It depends on the day. Sometimes I log in with the intentions to Raid, other times just to enjoy the day with no plans at all. So as StarLord said: "A bit of both!" 
In a game I know fairly well like LOTRO I pretty well know in advance everything I am going to do for the day, though I may guess wrong on how much of it I will get to.
In a game I don't know so well such as Pantheon at least for the first year or two I know what character(s) I plan to play and what the overall goals are - but obviously when I go into a brand new area I don't know what I'll find or whether an hour of play will see me filthy rich, in the resurrection respawn area or both.
I always have plan-B ready to go.
But I don't always get to it. Plan-A is decided once I log in and check into guild chat and or with friends to see if I'm wanted/needed by anyone.
Assistance to others goes out on a need before greed basis (corpse runs always too priority in EQ) if there's no takers then it's off to plan-B. Be it travel to a new home base, do some crafting or go to a dungeon and LFG.
Yes, sort of
Its usually once I log in- I check friends and say hello down the line then ask if they are doing anything. if yes: Can I help? If no: general chit chat and a pause while I think of something I could do where I could use them.
Sometimes I just want to grind and talk so I will broadcast- I am thinking fo heading to an area and see who joins.
Sometimes I find it awkward if I get a full group in a hard area and a friend comes on with the same questions and asks if I have any room and I have to say no. But that makes me want to look for a situation soon after like the next day where I can include that friend, sort of invite them first.
In the background I know of quests I want to do that need people, drops I would like to get that definitely need a group, and down the scale to small grinds where the monster is too tough for me to solo but maybe with even one more person it can work- this usually begets non-standard groups which I love- but needs like minded people.
Sometimes when putting together a non standard PuG, people will join then leave because we dont have an excellent slower, but we have a player that can slow, just not so much. My reasoning is, well we'll fight harder/cast harder and spend more time medding, but sometimes thats not good enough so they leave. Those that stay and tough it out however I try to remember.
Often I get stuck behind the " this is not worthy enough for me to invite soandso" and I need to be convinced that they are really ok with it. Like if I get invited to a PUG with a great fighter and healer and we have a great time named dead, no deathsin group or minimal. Then the next day if I want to go to another zone for a small grind just to see if I can get a certain drop like a bag- and they are LFG , I wont invite them because this was not the same hard group they brought me on before- so my idea is "not worthy" for those really good players and i will be inclined not to invite them, right away. heh
Sometimes I will have solo or crafting goals I want to reach and I will turn down groups or not actively seek groups.
Sometimes I will be haning out maybe crafting a bit and looking for a group - any group- to see where the wind takes me. This can be dangerous because it can make me lazy lol where I just wait around.
Putting together a PUG is somewhat nervwwracking because If its my idea, I feel I have to lead and explain things as well as insure that the group has a good time. What I really like is having a set group or people minus 1, where we really work well together and any additional "guest" can come along and we can work over their flubs but still not die and have a good crawl or whatever. Thats awesome.
I think what the game offers in terms of content, and specifically required content (i.e. in the case of keying for a dungeon or working through an epic quest), planning is often determined by the game itself because it's essential to complete a task. But, of course, there are other times that I fully enjoy playing without preparation and freely play more on a whim. So I quess I'm like disposalist in that regard.
In WoW I always planned out my gaming sessions. I knew exactly what I wanted to attempt or accomplish.
But that's usually not the same with games like EQ or I imagine pantheon. It's a more fluid game in the sense that is I plan to do A. And they Z comes along and interrupts that. Now I'm doing B.
I rarely plan ahead and usually login and hope for something worthwhile to get involved in. I used to plan more but family and work always come first so my play is always based on the often sporadic schedule. You would think that after the kids are all over 18 and most are out of the house there would be more time to game on a scheduled basis. Unfortunately, now the wife is bored and wants to get out more. Not that it is a bad thing but it does impact scheduling/planning for game time...
I'm half planner, and 97.7% OCD. And I don't care the math don't add up :D
I try to plan to do something specific. I understand when I log in it may or may not happen. When I'm set on doing something though, I need to see it to completion. Nothing worse for me than logging in, run for 30 minutes to help Lisa with her stuff, just to have Lisa tell me once we are 20% done that we will go help someone else instead, then we run around some more, and get halfway done with that person's stuff before everybody logs for the night.
Of course people that are not OCD will tell me "At least you got some XP". To which I will answer "And I haven't accomplished anything". I don't mind helping others. Let's just see it to completion (within reason of course).
Any plan after "will log in and play for some amount of time" ends up being subject to vast amounts of change, so I tend to just stick with planning to log in and then see what happens.
That is no reflection/criticism on Pantheon, the developers or the style of MMO in general, just a simple truth of online gaming generally, in my most humble opinion.
guild raid nights are carved out. tuesdays in vanguard were usually grinding out mana (for my cleric) or health (for the bard) pots from the arena as i remember it. guild harvest nights to get loads of adamantium. but free time is free.
that said there always seemed to be something i wanted to get accomplished, either finally finishing the new targ diplo baronets, killing the naughty elf for the strung moss lute or getting the 8th alt to lvl 55. the freedom was being able to drop everything to help someone get their griffin.
For the most part, I will go where the wind takes me. I sometimes might have a goal of camping a certain spot for a certain item.
A little of both I guess. I am pretty flexible. I won't give up a chance at a great group and good times even if it's not what I planned.
I just want to have fun. The rest is gravy.
I'm not sure everything can be heavily planed on an MMO.
Usually I'll log with something in mind (Farm something, grind exp here or there, do that specific questline or whatever) but I don't allways get the time or the opportunity to do it. It's why I remain very adaptative, and by having a flourishing to-do list, I can manage to switch from task to task as needed depending of my remaining playtime, opportunities or simply different envies.
