I have a twice around the room layout. the lower level is a table, about 24" deep in most places, the upper level cantilevers off the wall with L-brackets and a 1x6 or 1x8. A reversing loop or wye takes up way too much room and creates places you cannot reach. If you need to reverse engines, you can add a turntable, however that takes up a ton of space and probably will not work in a room of your size.
I suggest you try a single track design, with a few passing sidings and some industries. You can create an industry in each corner, with some industries on the front as well. You could create a hidden staging yard below the main table, with a track going down at the back, then hide the track with some building fronts. A second level would be difficult due to the size of the room. It takes about 20ft of uphill track to get to a second level that is more than 6" above the first level. However, with a hill, this could work. The hill could also hide the track going down to the under the table staging yard.
You may not have room for this idea, however it may be worth exploring in the idea stage. I spent over a year working on different layouts, and finally created something I liked in version 17 of my layout design.
Good luck and enjoy exploring different design options. This is a fun and creative part of the hobby and should not be rushed through, as you want to LOVE what you eventually build, as building is a lot more work than designing concepts.