yes, this is the exact problem I'm running into..
it's hard to tell which ones have an open or closed design for the top. I don't want or need a really high-end cabinet, so I've been looking at All-Glass, Perfecto & Oceanic at Pets-Warehouse.com-- unfortunately their product descriptions are really lacking, and the manufacturer's websites aren't much better. I guess I'm going to have to either email the manufacturers or go shop at the local Petco.