I would go for Wiz/Alc and Psi/Div, 'cuz they seem to me to be the best combos. Wiz and Alc seem to use the elemental realms, while psi/div obviously use mental and divine
I'm one advocating a 1 bishop party

my current one (Trynton)
Vi (to be replaced by RFS-81)
Madras
Human Lord
Hobbit Rogue
Human Samurai
Hobbit Ninja -> Ranger after crit kill and stealth maxed
Human Bard
Elf Bishop
The bishop's a powerhouse. I concentrate all the books on him, and have my others cast support spells. He's got at least 30 in all realms, since he does almost all the spellcasting.