First off, I have no idea what I want to do with Keldreth, my hunter. At first I was going to use her to farm Heroic Underbog in an attempt to become exalted with Cenarion Expedition and buy the hipporgryph mount. Only problem is her gear isn't good enough to for her to be able to solo the instance, so there goes that idea. For now she's on hold.
Blackbare will continue to be my main, running Heroics with my friends and guildmates to gear up. I've gotten some pretty lucky drops, and he's well on his way to having all purples. That's about all I use him for at the moment, but I will have to quest through Ice Crown eventually, even if it's only to get money from the quests.
Vonari is a little different. She will be running BG's and just be my PvP character for now. I have geared her up in a few instances, but I'm thinking she will just stick to getting most of her gear through PvP.
Avialle gets to be my guinea pig at gearing up on my own. I've been running normal dungeons with her for gear, and now she can queue for most of the heroics as well. I'm gearing her up strictly on my own, without guild help, just to see if I can do it without getting too frustrated with PuG's. It hasn't been bad so far, this new cross-server LFG tool really works well.
As for all the lower level characters, I probably won't be using them much for a while. Now that the endgame stuff doesn't require such long playing sessions to get anywhere, and the fact that I have 4 characters that are at that level, I think I will stick to playing them the majority of the time. Probably better to save the others for Cataclysm anyway.