I'm planning on doing the Netherwing quests so that I can fly around on Zoya in Northrend (he's the green one, pictured). There are a few other colors that I plan on purchasing as well, eventually, but Zoya will be my free one, the "earned" one.
I want to farm the mats rather than buying them all, so once I can fly fast I'll probably spend a few days farming in Outland to craft my Turbo-Charged Flying Machine. What engineer doesn't have one of these babies? ;-)
I've always planned to switch to the Oracles when I managed to get epic flying. Hopefully I get lucky and get the proto-drake from them fairly quickly. He's green (my favorite color, if you hadn't figured it out yet) and purple which makes him quite striking. Plus, all the proto-drakes evoke a sort of *Squeal!* "He's adorable!" reaction from me. I'd love to get the mini-pet as well, for a matched pair.
I'll get exalted with Wyrmrest Accord at some point, and the red drake is quite striking. Pity he's 2000 Gold, as I can't imagine collecting all that gold again, but maybe after getting a flyer that can really move farming won't be such an issue.
I already have the Blue Wind Rider, so I'd love to get the armored one from Mei Francis and pretend that he just "got faster with that fancy armor" but he's also 2000 Gold, so he's lower on my list.
Naturally any of the dropped (and therefor free!) flying mounts would be awesome. I have bad luck with such things, though, so we'll see. Most of them come from either extremely rare mobs that spawn in crazy, out of the way places, or from some Heroic dungeon or another.
Of course, all of these mounts being added to my collection get me closer and closer to the Albino Drake from the achievement. I've been wanting him for ages as well. In fact, if I had been smarter about all this mount collecting, I'd have had epic flying a great deal sooner. I purchased so many ground mounts as I hit exalted with the various factions without thinking about how much gold I'd need to finish training up my riding skill. Silly me. /sigh
Still, all of these things keep me playing and questing, and having fun in general. I've yet to get well and truly bored with this game and I can only imagine that Blizzard will continue to keep my interest with each new patch. It isn't (affectionatly) called Warcrack for no reason. ;D