Organize guest room - how?

Start by getting rid of everything that crept in there because "it's the spare room". Mine had become the place boxes went to die. After that guests mostly need small things: a clear drawer or two, some empty hangers, a spot to open a suitcase (a folding luggage rack is great), a lamp and a charger by the bed. Under-bed bins with lids are fine for your own storage if you need it.