Thanks for all the great replies. Currently, as mentioned, my layout is sitting on temporary sawhorses while under construction. The top is at 41" on those. I am having trouble reaching in the 2 1/2' to the middle, for laying track etc., without standing on a step stool. Since reach is a problem already, and I am going to have several operating accessories toward the middle of the layout, I am going to go lower. I just did a mockup with some leftover plywood, set at 36". I believe that is what I am going to use. It was much easier to reach 2 1/2' across the table, and this height does not require much bending over. So, got to go get the saw and get to work.
Jeff