Every year the Museum of Television & Radio hosts the William S. Paley Television Festival. For about two weeks, a dozen or so evenings are presented, each celebrating a different modern or classic TV show or personality. The evening includes a screening of an episode, typically, followed by a panel discussion with the creative team behind the show, which typically includes the show's creators, producers, and some of the cast.
We couldn't go to any of last year's festival, but this year we made it to three evenings: Battlestar Galactica, Medium, and My Name is Earl. All three were fun. The Earl evening was probably the most lively, though the Battlestar Galactica crowd was pretty vocal (and they knew their trivia). For Earl, they screened a couple of as-yet-unaired episodes, and the panel was lively and funny.
Any of you reading this is LA, the Paley festival is something I recommend taking advantage of. It's pretty much the first two weeks of March every year. I've gone to 7 or 8 evenings all told, and I always enjoy it. I've never gotten there early enough to watch the press meet-n-greet with panelists, or stayed late enough to go to the stage and try and talk with any of them, but that's also possible, if that's something you'd like to do.