Starting off the 2014 season I have seen a professional level game at 87 different parks:

• 16 currently active MLB parks
• 6 former MLB parks
• 19 Spring Training facilities (when used for a ST game)
• 9 AAA
• 6 AA
• 19 A
• 12 Independent 

I specify professional level games as two parks I've been to have been for the WBC (PetCo and AT&T).

I've seen games in 24 different states plus DC.  (I have yet…