You mention a 35" TT and round house. That is a great feature but I have found them to really gobble up real estate. Something to consider, do you want to model an engine facility or just turn an engine around?
Parallel tracks configured to conform to available space can be an efficient use of space.
A one or two stall engine house right next to the approach tracks keeps things tight.
Super short radial tracks helps with aisle space.
Finger modules with walk around ability can be a real asset.