Thinking about it, three clerics would be neat.  Have them related in faiths somehow.  Take different views of the same subject.
Magic
Evil and misuse / force of it
Good  over abundant and helpful
Neatral  balance and keeping magic from harming nature's way.
Or do that with Druids
Or do a Mage, a Cleric and a Psion and they can discuss the differences of their powers at family reunions.....