I am early in the game, and at this time I have an Undead Hunter, Minsc, Jaheira, Nalia, Anomen and a floater. Right now I am putting up with Korgans' grousy-ass, long enough to do the Book of Kaza quest. The way I figure it, I would do this in good conscience because it involved the "liberating" of numerous undead beasties.
Later I will use the floater spot to cycle NPC's in to do their quests. Ultimately, that spot goes to Imoen. The next-most-expendable person is Mr. knight-wannabe (Anomen). I just like the idea of having a really high level cleric in the group (not just a druid.)
"If you prefer, you could say EXPERT treasure hunter!"
--Gandalf the Grey, the Hobbit