Honestly ballparks are better off with a Seattle type cover rather than a Miami, Houston, Toronto, Milwaukee enclosed roof.
Harder configuration to close than a football stadium.
In Miami, the sun and humidity are awful! You need the AC down there, especially if you are a visitor from a temperate area. When the Marlins played at Joe Robbie, they couldn't draw flies for a day game.
In Milwaukee, you may have snow for Opening Day. It gets cold at times in early to mid April and late September or early October. My wife used to buy loose Halloween costumes for the kids in case they had to wear their winter coats under it. (It happened at least twice that I remember). Miller Park can be heated 30 F above the outdoor temperature. With the outfield walls and the roof open, it feels and plays like an outdoor stadium. I go to 3 or 4 games a year. The Midwest can get very windy at times. I remember hiding in the men's room at Milwaukee County Stadium a few times because of the wind chill. They had heaters and you could thaw out before going back to your seat. The fan shaped roof closes in 10 minutes or less and makes watching the Brewers a lot more pleasant on many days. On average, the roof is closed 34 games a season or 42% of the time. In 2006, it was closed 49 times. In 2009 and 2012, it was closed 24 times, to give you the high and the low for 17 seasons. The Brewers average 1 million more fans in the 42,000 seat Miller Park versus the 53,000 seat Milwaukee County Stadium. You will be warm and dry and see a game despite wind and rain.
Toronto gives you an outdoors feel, but I have only seen one game at the then Skydome and that was in mid June.
I have never been to Houston.