The current party I am using (all 6 my own creations) is working very well for me. A bit more powerful than the conventional 1 class characters:
very small SPOILER inside of this description regarding a thief ability in TOB
-Monk
-Sorcerer
-Orc Berserker
-Ranger dual classed to cleric at start of game (can cast cleric AND druid spells
-Berserker dualed to thief at level 9 (I am second guessing this thinking I should have gone with kensai because of a TOB thief ability that can negate the armor penalties of a kensai)
-And finally a kensai dualed to a mage at level 12
The party is slow to get going since you have 1 cleric and he starts out at level 1. also you have only the sorcerer as a mage until your kensi duals.
BUT this party is insane because everyone except the sorcerer can walk right into melee and just TEAR it up. once the kensai/mage gets his kensai abilities back at level 13 the real insanity starts. He will have much better ac than a normal kensai due to his robes and spells. your monk will be very powerful by then as well.