I like reading about other people's group comps so i thhought i might as well post some of mine. My highest group is currently 71. Im running:

Prot paladin
Cat druid
Fire mage
Demon lock
Holy priest

The nice things about this group:
Three classes capable of healing and rezzing
Easiest tank to box
Best healer in the game
Portals
Soulstones
Decent aoe when needed

Bad things?
Ummmm... I cant think of any, reallyl i guess if i had to make up something id say i cant use mail drops. Also, wotlk quests in borean tundra dont have shit for paladins!! But this group comp is lots of fun.