My girlfriend has rooms about that size for her kids and both have queen beds. She put the bed on the longest wall, a night stand on one side and a desk on the other side of the bed. (She got the desks and night stands at Home Goods.) Make good use of your closets, built-ins are a good idea here since there's not much room left for furniture. She did squeeze in an armoire in her daughters room, but it's very tight.

The kids end up playing and hanging out on the beds since there's not much floor space left. Works great for her daughter, but when her son has friends over they end up jumping on the bed and bashing into the walls, LOL, boys will be boys!