Jerry,
The main or first level of my layout is just a tad over 48”, which makes the clearance from the floor 43-1/2” after the QuietBrace, plywood, and 2x4” frame. The second level is 9” over that, so about 57” from the floor. The “L” train is about 8” higher, making it about 65” from the floor. Then I have a subway that is 2” lower than the main level, but it is only about 24 Sq-Ft.
I really like the clearance under the main level, and people don’t seem to mind the fact that everything appears ‘high’. I have several observation platforms that are 16” and 10” high so people can get a better look at the top levels. The “L” train looks real when you stand on the floor and look at it. My basement was a 9-ft pour, but I installed the suspended ceiling right at 8-ft.
Good luck!
Alex