I've been going to the Huntsville Hamfest in Alabama since '95 and it's a great hamfest. 100% indoors with a good mix of vendors, swap tables and manufacturers. You get a break on a room at the Hilton across the street by asking for the hamfest rate. Like all the others, it's been getting a bit smaller over the years but still a great hamfest. Dayton and Huntsville are about all I go to anymore.
It's in August and more info can be found at www.hamfest.org