NWN.. teh weee!
Monks are pretty good once they get to a certain level. You sure it isn't a racial bonus that is saving them from mind-affecting magic (elven?). I don't believe that their magic resistance is beefed up to absolute rediculous levels until they are well above level 10, no? (Don't have my guide in front of me).
Also, regarding treasure and XP.. have you patched the game yet? The original out-of-the-box version gives way too much treasure and XP and was toned down to more appropriate levels. As it stands out of the box, you can easily reach level 20 by the end of the module whereas with the patches, I think you're lucky to max out around 16 or 17 by the end.
I once made a monk but for my character, gave him a katana instead of using hand-strikes or Katas/Ki's. A lot harder to do well, but it was really quite fun to play an unbalanced and non-buffed-to-the-freaking-max player.
For extra fun, try playing something like a barbarian wizard/sorcerer or bard. Hehe..
I think the original game/module was easiest to complete with the sorcerer class. You have your henchman, familiar, and summoned beastie on top of your insane area-effecting spells and self-protection stuff.
I think one of my most kick ass solo characters was a elven thief/arcane-archer guy. It was just absolute rediculousness. Hide in shadows, launch fireball arrows and various other poison/effect arrows with the sneak attack bonus.. pretty nasty.