I run:

UA/Prot Warrior + Ret Paladin + Enh Shaman + Blood DK + Resto Druid for PvE
Arms Warrior + Ret Paladin + Enh Shaman + Unholy/Frost DK for PVP + Resto Druid / Holy Paladin for BGs (Disc Priest partner for Arenas)

I did not design my team around optimal PvE performance, but it work's quite well. These classes/specs have zero proc management and fairly simple priority sequences, so I find it easy to get fairly close to optimal performance with each class using spam macros.