I started with my priesty, healing disc/holy through most of wrath.
Leveled my shaman as my first alt, with an intent to play it as enhance. Leveled as enhance, hit 80, defaulted to what I knew (healing) for shorter queue times to gear my enhance set. Have since never played the shaman as enhance, only resto and occasionally ele.
Tried again to make an alt with a different role. Leveled my paladin to 60 with RaF, tanked straight from 60 to 80, doing nothing but dungeons, hit 80 and started healing heroics until I could get def capped. Ended up healing raids on the paladin in no time, and the tank set was never used for anything besides heroics and VoA. >.<
Gave up on any fascade and leveled a resto druid to 80.
All but the druid (my least fav to heal on) are 85 now, and raid ready. Priest is still my main by far, and the alts haven't gotten as much love as last expansion, but I love healing. I love the differing tools, and the synergy with certain specs. I like the challenge, and being able to talk to other healers of any class about the role as a whole. I find knowing the ins and outs of all of them make you a better healer in general.