I've been trying to level up several classes/jobs at once.

I finish off my daily roulettes on a level 50 characters for the tomes.
Then I decide what I want to do.
If I want to primarily run dungeons for XP I queue as one of the tank or healer classes. Those are pretty much chain instance pops and you barely have time to repair and get a drink between runs.
If I want to work on hand or land classes I queue as one of the DPS classes and then work on trades kills or gathering while I wait. Obviously those queues are a lot longer so I get a break from tradeskills once every 30 minutes or so.