It depends on the year. One year I did what turned out to be 14 cons and other assorted con-like events. (Ren Faires ect). This year, due to being without a job for 3 months, and saving for another 6 before I lost it, since I knew it was coming. I only did 6. And three of those I only did because I got in free.
Wicked Faire, Steampunk World's Fair, Castle Point Anime Convention, Anime Next, Dex Con, and NYCC. But really except for Anime Next and Castle Point they're all different themes. That's my secret. Very rarely do I double up on themes of a con.