In Wizardry 7, I usually played this party:
1) Fighter --> Lord
2) Thief --> Ranger --> Bard
3) Priest --> Valkyrie
4) Mage --> Samurai
5) Alchemist --> Ninja
6) Psionicist --> Monk
This worked out VERY well and yielded an extremely powerful party, as I would retain the magic users until they got the majority of their high-level spells & lotsa mana, then convert them into their advanced fighter classes. For example, the Mage would convert to Samurai, then finish learning the mage spells & could also wear good armor & was a very good melee fighter as well (ditto the others).
I am not sure that this will work well in Wizardry 8, as they do not start over at level 1 in the new class...it will mean MUCH slower advancement in the new classes' skills/powers/etc.
Anyway, just my two bit's worth...
--Greystone