It might be helpful if you post your SCARM file so those using SCARM can experiment without having to guess at track sizes, etc.
From what I can tell, all your "S" curves have straight sections in them, but I don't know if that's good enough to alleviate problems, especially with longer trains. Either way, if those loops are 4" deep or more I see access issues for the lower left corner.
I've read here that while the curved switches and double-crossover look nice, they can both be problematic. I have no experience with them though, so I don't know how true that is. Retail price for the double is $400 whereas four 11° switches comes to $300 and gives you a little more flexibility in design. I agree with Tom that durability and operation should override price concerns when purchasing switches.
Since the stairs comes up where the large rectangle is, I assume there is no door to contend with and probably no windows either. And when it comes to 36" wide decking, I believe you're looking for ideas for sidings and landscaping to fill the space. With 36", I wouldn't run the track close to the wall because any reach over 30" can be a problem depending on how the benchwork is, how tall you are, etc.
