I've been to a handful of conventions held in the D.C. area over the last 8 or so years. I originally did a bunch of panels the first few times I went but quickly found that the quality was extremely hit or miss so now I only go to maybe one if it's really specific to an interest of mine. The AMV contests are enjoyable though, albeit a little long.
Otherwise I spend most of my time in the vendor hall or artist gallery, checking out the cosplayers, and occasionally play some of the arcade or touhou games in the gaming hall.
Really though I couldn't see myself going more than once or twice a year, and when I do go it's only for a single day and not the whole weekend. It's certainly fun and I enjoy it but after a while I run out of things I want to do or see. It does feel nice being surrounded by like minded people especially having grown up not having anyone to talk to anime with and effectively hiding my interest in it. It's just comforting in a way.