Beverly asked which are better, the big or small events, and I'd have to answer, It depends. The best reason to attend any conference is to get our names out there. Unlike non-fiction that's usually discovered by looking up the subject matter, fiction is found by knowing the author's name, our names, period. I've been lucky enough to always have a panel or two, and have often moderated, as well. Those rows of people listening to the chatter will get to know you and, hopefully, they'll tell their friends. THAT is the best reason to spend all the money (and it DOES add up). Another reason, a more personal one, is to network, meet old friends, share the gossip--all the social reasons for going.
I always do the simple math that compares what I'll "get out of it" and how much it's costing me. It's not just the travel fares, the cost of the conference itself, the hotel, food, and everything else, but I live on a working ranch with a husband who teaches in the Bay Area and anytime both of us are gone we must hire a "ranch sitter." I certainly won't sell enough books to cover all that, but I may, if I'm lucky, meet some nice, new folks and get my name out there and both of those will pay off in the long run!