I've been to Gencon only once, however I'd really like to go to more conventions (mainly just GenCon), however money is one the primary factors that I probably won't be going.
I haven't gone to any cons yet, mainly due to my lack of being able to attain the proper transportation and a lack of people that I know to go with, however all that seems to have changed this year as I plan on going to Gen Con (in Indy) with my D&D group .
I go to gaming conventions because it is fun to hang out with like minded people, play new games and in some cases, "get away from it all", in other words, not have to worry about dog walking, work, family, etc.