Obviously the most minimal party is solo, but that also takes some of the fun out of the game. I'm interested in small party combos which retain good interactions / chemistry.

A combo that I found effective was: Me (fighter/thief), Jaheira, Aerie and Mazzy. Mazzy brought up the rear (she keeps saying "I go forth" which sounds like "... fourth" -- surprised me quite a bit) which is perfect for the best archer in the game.

That smallish party is effective, but not the most fun. Jaheira fights a bit with the other two. (Jaheira might be quiet because she was out of the party for a while -- she became Imprisoned and when I freed her she acted like I'd ejected her from the party voluntarily.)

I suspect the most "fun" interactions come from parties that mix good & evil characters. I've been playing basically good parties so have little experience with the Dark Siders. I wonder if a party consisting of an evil fighter/thief and the three easily available evil NPCs (don't know if there are more -- I'm thinking of Korgan, Viconia and Edwin) would be more fun.

Finally, which three characters would go best with a chaotic neutral bard character (Skald in particular)? Mazzy, Jan and Jaheira come to mind.

Strictly for character interaction, the following combos come to mind:

The Lovers: Play yourself as a high Charisma male character and take all three of the Romance females - Jahiera, Aerie and Viconia. If you have access to it, enable all three romances and watch the fur fly!

Charlie's Angels: Play yourself as a male (Thief or Bard) and take Nalia (Drew Barrymore,)
Aerie (Cameron Diaz,) and Jahiera (Lucy Liu.) Make sure you name yourself Charlie. Later on, pick up Haer Dalis for some extra fun.

Good Vs Evil Debates: Play a neutral character, then take Keldorn, Jan and Korgan. Lots of good bantering with a possible challenge battle. Easily exchangeable with any good and evil characters.

Don't forget that if you decide to play a Multi Player mode game and have access to the proper editors, you can make your own scripts for your charaters (that's a LOT of work though!) Enjoy!

Fighter/mage
Fighter/assassin
cleric/mage (or full class mage)
ranger/cleric
all but the cleric/mage dualclass