In chronological order:
Atlanta Fulton County Stadium (Braves pre Turner field home - 2 or 3 times)
The Ballpark in Arlington
Hank Aaron Stadium (in Mobile, Padres AA team)
saw the Cubs vs. the Twins in the New Orleans Superdome for preseason
That's it for me.
Hoping to do Fenway, Yankee Stadium, Camden Yards, and Wrigley again.