My first focus will be to level my druid to 85. I want to explore all the new zones, rediscover the old world, do all the quests I can find, level my alchemy and herbalism and finally get to know all the new 5 mans. After that the raiding can commence! Main spec will always be resto but I'll likely level as Feral and then probably go Resto/Balance at 85.
Unless I'm mistaken there will be four new starting zones in Cataclysm. One each for Gnomes, Goblins, Trolls and Worgen. When my druid is raid ready I'm going to check out these new zones fully before getting other alts to 85. I'm currently missing a hunter and a priest so I'm planning a female worgen hunter that will probably go for Beast Mastery. A gnome female priest sounds cute and she'll probably go dual spec Shadow/Disc.
After having seen the awesomeness of the troll druid cat form I'll likely roll one just for fun that will be Feral. I've thought a bit about what class I'd like to play as a goblin and I think I've decided upon a shaman! I already have a low level Draenei one but I'm not sure about that one. How can I resist those mechanical totems? The goblin starting zone is by far the one I'm looking forward to the most, it just looks amazing! I haven't decided on a male or female goblin yet but it will be Elemental for sure!
When I'm happy about the new zones I'm guessing my mage will go second as fire spec to 85 and I want to level enchanting and tailoring for new bags and enchants. After that it's likely my DK that's next as Unholy. He's sort of my casual raiding character and I'd like to alternate between him as melee dps and the mage as caster dps when doing instances if I'm bored with druid healing.
My rogue is hibernating at level 70 and I might level him through Northrend when I'm done with the other classes but that's going to be a long while.
When not raiding my interest lies right now in my lvl 47 paladin and lvl 40 warlock. Those are a lot of fun to play and I'm guessing I'll level them and gear them up now until Cataclysm hits.
That should keep me busy for a while :D