NECRAILS and RSJB18: Thanks for the advice on the switch access. I didn't think about that being a problem, but I can see why it would be. I reconfigured the layout and moved all the switches on the upper level so they were more easily accessible.
I did a layout a couple years ago that was higher, closer to 48" for the lower level. I decided that was too high. So, I decided to lower this one. I do have small children and that was definitely a consideration. Also, because the layout is so wide I wanted to have as much arm reach to the center from the sides that I could. I definitely understand the issues of bending over and doing wiring underneath. I will figure out what works best for my situation.
Thanks again for all the great advice! Here is my reconfigured design.