So here's the plan. Over the next to years, I'm going to run between four and six campaigns. One per semester (not counting the one I'm running now) and maybe one this summer and one the next, depending on whether the other GMs in my home group decide to run anything, and whether I need a break at that point. If one of the semester campaigns really takes off, and most of the group involved will still be at school the following semester, I'll consider extending it for another half a year or so. But barring that, I'm going to indulge my "gamer ADD" a little, since it's fairly convenient to do it this way right now.
I've got a lot of different games to run. I'm running Traveller now, so that's off the list, but sometime in the next two years I'd like to run (or play) Vampire or Mage, futz around with Encounter Critical, start up a OD&D/S&W megadungeon, and maybe even give 4e D&D another try. A couple of my players have been bugging me about running a sequel to my Arcana Evolved game, so that might get dropped into the lineup, and part of me wants to see what I can do with GURPS, now that I'm a little older and a little wiser. And that's just games I've already got -- nevermind the countless new obsessions I'll likely accumulate over the next two years.
I've spent a lot of time grousing about how I'd like to run long, epic campaigns, but really, I've had a lot of success with short, focused games. The players like the sense of accomplishment, and I like being able to move on to the next project. And right now is a pretty convenient time to be running a lot of short campaigns -- the semester structure encourages it, lots of turnover in the player base, fairly easy to find new possible players. So for now, that's what I plan to do.