It is hard to focus entirely on a single character in WoW. Unless a person can PvP, raid, or dungeon crawl all the time or has an extremely limited play schedule, most players create an alt or two or 10. Wrath made alts easy -- hit 80, run a few dungeons, full epic gear in a day. Cataclysm may have eased the leveling process, but gearing and rep grinding on a single character is much slower than in Wrath. Also, there are not a lot of successful PUG raids to get an alt into. Most guilds haven't even killed all the content yet in normal, let alone in heroic. So the question remains: How to deal with alts?
I had seven 80s in Wrath, and all of them had at least full 251 gear before Cataclysm launched; heck, I had the ICC drakes on two different characters. Yet in Cataclysm, I find myself leveling them much more slowly and in fact didn't touch any until I had gotten my main through heroics until the point that justice points became useless and I had been exalted with every Cataclysm reputation except my guild. Even then, I concentrated on a single alt primarily hitting 85, then getting some gear.
But I found something interesting: Merely doing cooking and fishing dailies every day in Stormwind, my other alts are gaining experience much faster than I thought they would. I hit 81 on a few alts without ever having left Stormwind, except for the initial trips out to Hyjal and Vashj'ir in order to open the portals. One the other hand, I have a friend who leveled all his toons to 85 before deciding which one he was going to focus on.
So how are you dealing with your alts in Cataclysm? Are you leveling them all or letting some sit? Did you change your main?