Which class to choose?

I'm going with an evil misanthropic monk, though I recall hearing that the passive bonuses that Barbarians get make them ridiculously good soloers.

Thoughts?

For baldurs gate 1 go with monk, Monks can fight and have stealth. Though they have a tough beginning. I would steer clear of barbarians. They have no stealth and therefore they will die from being in melee too long. Sarevok is a better fighter than whatever fighter your main character is (having a +6 twohanded sword doesnt make things easier.) You could also use a fighter/thief multiclass. I soloed the original game with that. Actually it was a dual class, but thats almost the same.

If your talking bg2, a barbarian can solo the whole game...except the expansion pack. So can the monk. Check out the builds under gamebanshee.com. There are solo guides to all this by people that have actually done it. I've soloed bg2 with a monk and it was a lot of fun.

Cool, thanks.

Is it really going to be sufficiently tricky that I will need a guide to survive, or can I just learn as I go along without it being too terribly frustrating?

You dont need a guide, but the guide is just proof that it can be done. Thats all it is. The only classes that really would not be able to do it are solo thief classes. Unless they use ranged weapons to the max. I still recommend the monk.

Problem with Monks is that they can never get their fists past +4 by throne of baal. Cant take on demi-lich :(

Well there is always the overused kensai/mage....

+4 can hit any unmodded enemy in the game, with the exception of the Lesser Demon Lord in Ust Natha, who can be hit by +3 or +5 but is immune to +4.