2cents worth.
Some folks would agree with Jim about a range of your work and I would agree with his reason, but many gallery owners would recommend a coherent set of images (the popular phrase today is a "body" of work). Sitting here thinking if I was you, I might go with my gut feeling on this, or, in other words, what I was most excited about.
I would also say, go with 10 x 10, no smaller, unless it's a really small space, or unless your images work better small (the size of the room, and the available space are two different things). If you have any prints framed, you might be able to try some out after closing, just to see the scale of them in the space. Doing this once, I reprinted everything from 11x14 to 16x20, just because of what one of the 11x14 images looked like in the space.