I think you are actually going to draw more attention to the squareness of the room by putting in a huge round rug. It will act like a bulls-eye, and all the corners will be emphasized where the rug doesn't reach. Plus, all of your furniture in the space will be half on, half off, the rug, which will break up the round effect anyway. I would think about adding a couple of smaller oval rugs, perhaps on either side of the bed. Then use your fabrics, accessories and art to bring in softness and rounded corners. Fabrics with softer prints, curvy patterns, curvy lamps, round accent pillows, pretty plates on the wall, a round mirror, etc.

It would depend on the market. Is this an area for singles, couples, kids? If the area is mainly singles, then a larger bedroom might attract more potential buyers, when you do sell. I mean, everyone else will probably have the two small bedrooms. But if it's couples, kids, etc. then the two bedrooms will be a better choice. Any chance you can make the smaller bedroom a den with double doors, if you decide on that option?

I did that in my guest room - no problem at all. The carpet is pretty low pile and the rug is a fairly thick sculpted type oriental. I have no pad under the rug. I also have a very short, dense wool oriental rug on the carpet in my living room. That also works fine. I have all these rugs on carpet because I moved from a house with wood floors to one with more carpet. I hope to get rid of the carpet someday when I feel like moving everything again. So then I will need the rugs and in the meantime I can't stand the plain beige carpet. In another room I have a thick wool runner that covers the width of carpet from the deck door to the wood floor in the dining area. It has no furniture on it that holds it in place so it ripples a bit. I need to find a way to keep it flat.

What did you do with the other twin? Do you have friends from college who come to stay? If you still have the other bed, there's the option of putting the twins together and treating it like a king. Get an inexpensive headboard from Craig's List or make your own out of plywood and fabric. I forget what the stuff is called for padding, maybe batting? You could even just nail the covered headboard it to the wall to keep it simple. Or use the twin sheets on the beds but push them together and just dress the top as a king. Separate them or not when you have company.