3/4" Melamine is my favorite for cage building but if you don't mind the extra work getting some good quality plywood, sanding it, staining it, and sealing with a good poly and silicone is the way to go. You can bring out the grain of the wood and make some outstanding looking enclosures. In my opinion, if you are going to have over head lighting, the screen used for the light(s) is plenty of room for air exchange to keep things from getting stagment. As far as height, not sure if they will use it much. I have always kept balls in racks