Hi Russell,
The use of the sectional was to get the alignment and curves correct.. If you like the spacing and location of everything, I'll convert it all to flex and fix the fitment issues.
it appears a somewhat freeform flex will be needed on the fireplace exit of the bridge.
Which turntable do you have or will you use? The placeholder in there now is a 24" 2 rail.
One other suggestion is to lengthen the Roundhouse peninsula by 16" to have room to park the engines in front and maybe sneak in a side whisker.
Good idea to double the bridge for appearance. Again, that can actually be whatever Dad wants it to be. Scenery on wood, girder or trestle. I can point you to a few threads with different methods to build it.