Good Morning Mark,
I'm getting ready to leave for the World's Greatest Hobby Tour in downtown Phoenix, so I don't have time to play with this right now. Not sure what time I'll get home, but I'll check in to see if anyone has taken a stab at it. If not, I'll work on it then.
Is my understanding correct that one of the turntables will be higher than the other? The one at the top? There is a Figure 8 in the center and I believe the idea is for the bottom half to be an over/under affair. Is that also correct? My concern is all those switches close to the intersections (circled in blue). You don't want switches on a grade, so it's going to be awfully hard to raise those tracks the 6" or more you'll need for clearance.
The tracks going across the top are too close, so that will also need some serious modification.
Widening the lower circle for access may not be too big of a problem, but I'm hoping we can get some regular switches in there, not the curved ones that are shown. I know you plan to use Ross switches, but how much trouble are their curved switches, especially since they will be in constant use?
Lining up with the turntables is probably going to require the use of flextrack, so I hope you're ready to learn how to bend GarGraves. 
