In new house construction, I am wanting to build a steam shower/bathtub room. You first walk into the shower and then tub. Actually, I have two questions. Are there any products besides tile that I could finish the room surfaces with? I hate to fight the mildew on tile grout! And, what kind of waterproof windows and exhaust fans would I need to put in the room so it does not become too damp?
Thanks for your help!

You can use marble slabs, we use to do a lot of that before tile became so big. As for the waterproof windows you may need to call a window company for that, at least I don't know of one to recommend for you.
As for the fan, get one with the most cfms. Now they also make some just for a steam shower, that has a light with it, check Lowe's or home depot