It sounds like you're a big fan of baseball and it's great to see you're not picky at all with what the stadiums would look like. I'm sure the creator will do a great job with them.
I like the idea of having the roof closed most of the season for some of the stadiums, it adds a new level of realism to the game. I noticed that you're requesting natural and artificial turf surfaces, it's great to see variety in the game.
If you're interested in retractable roof stadiums in real life, I would recommend checking out
Indianapolis roof company. They might be able to provide you with some information and inspiration for your requests. Keep up the great work!