What I want to know, especially of the veteran players, is whether you have the type of victory you want to go for in mind before you start the game; or do you decide what type of victory looks the most attainable after you play a bit and can assess the situation?

Obviously within reason there is some planning if you choose your leader. An aggressive leader probably isn't the best for a peacenik cultural victory, etc. But within those limits, do you start up your game thinking "I'm going for a cultural victory," or play it by ear after you start?

You have to plan for a cultural victory, which is why I never go for it. I always play by ear and go for whatever victory that feels best. I never decide before I hit the Industrial age, unless I started the game with to test a certain strategy or something similar.

Somewhere in between the two alternatives. You definitely can't come into a game knowing what VC you'll get, not at higher levels at least. Too much depends on your map and your opponents. But you do need to develop a plan relatively early on and make it happen. If you wait too long, you're going to be missing opportunities and wasting time. I'm struggling to find the balancing point at Emperor at the moment.

For my own amusiment I normally disable all but one of the victory conditions when I start a new game, just to see if I can do it with whatever hellish starting location I get (it's never right for the victory type). When I do that I definately have a plan. On the rare occasion that I do play with multiple victory types enabled I just adapt to whatever feels right based on how the game is progressing. Truth be told, it's normally either domination or diplomatic. I can't sit idle long enough for the turns to run out and I never play with the space race enabled becuase I find it too easy. The only cultural victory I have in Civ 4 was a complete accident, it was a confined map and I was just trying to keep my borders expanding or at least not collapsing on me.

If you plan to be a war mongerer you need to start early with your strat before the AI builds itself up (better get iron/bronze). If not, I like to plan my victory once I learn who all my opponents are.

I play by ear...

...though that's mostly because I don't know HOW to plan ahead yet. :lol:

I try to be competitive on all victory options. I have had difficulty winning a cultural vic but I have not played strong wonder builder civs, yet.

I don't really plan ahead, which is probably why I haven't managed a Diplo win yet. I only start thinking about my standing with the AI's around the time when I start building the U.N., and unlike in Civ III, that just doesn't work...
I think cultural victory is the one where planning ahead is most crucial. That's probably why I've never even attempted one yet.