Well Nick, 10'x12' is pretty limiting. But it is what it is. I like your Version 2 with the straights. Keep in mind you will definitely need access hatches. It's not a matter of if, it's a question of when. As well as derailments, you have to consider track cleaning and debris removal. Here's my recommendation. And hand-holes might be needed in the 2 corners at the right side of the room as well. A derailment in the tunnel at the back right could be a problem.
Good luck with your planning!
You're right, it certainly is! I'm coming from N scale (tired of the tiny tiny pieces), and oh how much room that would be! With my reach, everything should be accessible in the south west corner, since there's only a short knee wall there- I should be able to reach right over that. But yes, the north east corner is certainly the tricky spot. I was actually playing around with a version where I took all the switching on layer 2 out of the northeast corner and put it in the southwest corner. I may completely eliminate the long 45 at the corner too. That way, all the switching would be better accessible, and the only thing in the northeast would be curves, which would be simpler to access with a smaller panel, or access hole