I 10 boxed during wotlk with a pvp mindset.
If I would do it again:
Caster - 8 elemental/ 2 resto........ Very easy, bursty and 8 chain lightnings......
Melee - 7 or 8 dks with healers

When these two teams are at max lvl they could easily mixed mixed together for a 10 man pve team too.