For the last few days, I've been pretty focused on leveling my paladin, so have managed to get him from 42 up to level 50. I've got to say that leveling the paladin is a lot of fun. The guy seems to be pretty unstoppable.
Adding a few core talents like Art of War along with getting Hammer of Wrath has made for a formidable rotation. I also just picked up Crusader Strike which gives me something else to do while I'm waiting for Hammer of Wrath to pop. All in all, it's big fun and seems to make for very fast leveling.
I'm still torn about my plan to switch and try to level through tanking once I get this character to Outland just because he's so much fun to just level through questing right now, and strangely enough, even for the 5th time through, I'm not entirely tired of the quests yet.
When I pick up my shaman next, I may switch him to resto and try the leveling through instance approach with him (although I may just quest from 28 to 40 first - seems like that might be a pain without Chain Heal).