Well my warlock is almost 80.  Can't wait to get there.  Not because I want to rush to 80 but simply most of my guild mates are at 80 and are constantly running heroics and beginning to raid.  I really enjoy running instances with my guild and thus feel left out.  So I will focus on doing quests and focusing on leveling that last level ASAP.  Then i can slow down and continue doing quests to get more lore and help my reputations.

I really enjoy questing in Northrend.  The quests are beautifully tied into the lore that you get to explore.  Plus the mechanics of operating machines, guns, flying dragons etc are really cool.  My next toon to get into Northrend will start off in the other entry level zone so I can do all the quests there.

As far as my other two favorite alts, my AOE mage and paladin, I also want to get back to play them.  I think my goal is to get my mage to 50 so that I can level my enchanting for DE purposes.  Then I will work on the paladin.  I do want to havea  healer class in end game.  However, I did get tired oh my druid, who is now 49.  Druid healer was my original goal, but I think i might go with a paladin instead.  I love AOE grinding and questing.  It's just too much fun to pass up.