What do I mean when I say "2 Healers" or "5 DPS" or whatnot?
Generally, we run with one druid tank and one warrior tank.
Our two primary healers have traditionally been a paladin on the tanks and the a priest on the raid. If we do an encounter with a third healer, the third is usually a druid. The priest is sometimes holy, sometimes discipline, depending on the encounter. We almost never run with a resto shaman. We don't like green light. We've gotten addicted to paladin heals to the point of an unhealthy unwillingness to try some encounters without them.
Our DPS is a random mixture from the following pool: 3 hunters, 1 deathknight, 1 rogue, 1 elemental shaman, 1 ret paladin, and 1 balance druid. That's right, we almost never run with a warlock or a mage. Why? Mostly just discrimination--we hate clothies.