Choose your own (floor) adventure

I've come to the point where I need to choose what to do with my bedroom floor. My design sense is failing me, and so I've decided to throw out the question to everyone I know. My bedroom is a large garret bedroom* with now-white walls and low ceilings. The floors will soon be well-sanded plywood subfloor - that's the stuff that's usually there to support your carpet or tile, and it's not usually exposed. The correct flooring choice would probably be to install carpet, because the sound of footfalls carries easily downstairs.** Instead, I plan to keep the plywood exposed and lay down a rug. If necessary for resale, I'll install carpet when I'm moving out.
I'll probably end up choosing an oriental rug, because the only other options for used rugs are super modern, and that just doesn't fit into a 70-year-old-house. So, could you all squint at the pictures below, picture a medium-sized oriental rug, and tell me what color the floor should be?

Choices:

1. Painted squares 
2. Stained dark brown (this will never look like real wood flooring. The most I can hope for is that people don't particularly pay attention to the floor.)
3. Unstained, but covered with a clear coat. Think industrial/Chipotle aesthetic. Something like this, but without the stencils.
4. Painted a dark brown

I'll add a caveat about how I know this is not the "right" way to do things. Plywood is soft so it's going to dent easily. I've heard of people having plywood floors for 3-5 years, but nobody keeps them for 20. So this is a "good enough for now" choice for me.

*According to a dictionary, a garret is "a top-floor or attic room, especially a small dismal one (traditionally inhabited by an artist)." I'm trying to avoid the "dismal" part.

**I had planned on new carpeting, until one morning when I was cleaning up dog vomit from my spectacularly ugly existing blue-and-red carpet. I realized that I could not bear to spend hundreds of dollars on new carpet that my animals would most certainly throw up on.