Place a towel bar (or maybe 2) on back of guest bedroom door. This will keep your guests' towels, facecloths etc., nearby for them and free up the bathroom of "too much stuff."
ThriftyFun is one of the longest running frugal living communities on the Internet. These are archives of older discussions.
This is my #1 hint for decorating a guest room and doesn't cost a thing. After you're done, and it looks beautiful , spend a night or two in your own guest room.