What about the original Baldur's gate? I was looking at that a bit more, but I've heard good stuff about BG2 though. :)
If you're not used to AD&D, it might be worth doing Baldur's Gate 1 first, due to it being a lot more restrictive with the number of skills and options it throws at you (partially due to it only going from level 1 through 8 or so, while Baldur's Gate 2 starts where the first game ends, both in levels and story). Some people have a very hard time with the very beginning of BG1 though, especially if you don't play a fighter-type character (a level 1 mage, or even thief, doesn't allow for being hit a lot).
Hmmm... Now you say that, ive come to a bit of an odd decision. Now I can't decide between Planescape Torment and Icewind Dale. I did some more research though, and the fact that you start with six players in Icewind Dale pulls me towards it...
Note that there's nothing stopping you from trying to run through the game with a single character :-) You don't have
to create a full party.
I would say that Icewind Dale is much more forgiving to modern players and newcomers to the Infinity Engine games, where Planescape might feel much too slow.