I've only done a one-shot before. My old college roommate got a bunch of us together to do a one-shot Burning Wheel game (or a modification of Burning Wheel, I can't remember) for his younger brother's birthday. Doing tabletop campaigns are just too much of a time commitment for me, though, and all of my friends that do tabletop games are really into having long, intricate plots that require everyone to be there at a set time every week. If my schedule wasn't so unpredictable, I'd be interested in playing more. The one-shot was pretty fun.