If you plan on doing heroics, a PvE team with a tank and four of another class works well.
Paladin/DeathKnight + Shaman's, possibly one resto or all elemental.

A lot of people like Boomkins, mine are mid 50's and fun.
Shaman team is the most common, have that too.
5x BM Hunters is pretty good, thinking this will be great for dailies.
5x Disc priests was a pain at lower levels, but is getting to be a lot of fun.
Multiple Demo Warlocks would have been fun, but RAF is almost over.. Health Funnel, talented/glyphed is strong.
Mages with a S.Priest is popular, not sure if it can heroics or not.