Considering what Terry Pratchett has been diagnosed with, he may not be attending conventions for much longer. I'm definitely going. Other GoH's include Esther Freisner, Diane Duane and Peter Morwood. Membership is listed as $60 through the end of March, they haven't updated since.
I've been reading Pratchett since, IIRC, the fifth book (Weird Sisters?) which I got through the Science Fiction Book Club. He is one of the few authors, perhaps the only one, that I'll buy on sight when he has a new book out. Yes, Thud! was a little weak, but I think the body of his work is very strong.
http://www.nadwcon.org/
