Since the question has been posed, let me answer it. Visiting every MLB stadium is on my life to-do list. So far, I have visited the following (ranked in no particular order):

Cincinnati Reds (Do the Diamond Club seats just once in your life!)
New York Yankees (There's nothing like taking the subway to a game!)
Detroit Tigers (Love the new joint, it rocks)
Chicago Cubs (I LOVE WRIGLEY!)
Boston Red Sox (Yawkey Way is a great fan experience but the seats harken back to the 1800s, for real)
Chicago White Sox (Is this the new place? Hard to tell)
Colorado Rockies (Beautiful place, love the people of Denver)
Baltimore Orioles (Cool stadium, a great destination)
Tampa Bay (Why don't more people go to games there?)
Cleveland Indians (Well, this one is in the right order, I can't root for anything in Cleveland!)

Tonight, I am visiting the Kansas City Royals stadium and have summer plans for Pittsburgh and Washington, DC. After this summer, I will have 18 more to go...give me a couple of years!

How many stadiums are you up to?