I, too, print small enough to allow mounting and matting on 16x20 board. Anything larger seems really hard to deal with. Like anything in photography the larger you go the more it costs. Plus, I like a lot of mat around the print. Like Ann said mount them so they are all verticals as it makes the hanging of the show easier. To Black Dog's (if that is really your name )question: Yes, 20 images seems to be about right for a small gallery show. Maybe 30/40 for a really large space. However, all the work should be strong and hang together, in my opinion.