At such short notice Geneva hotels can get a little booked up. I do beleive the Hotel Intercontinetal in Petit Sacconex is not full but I am not sure about the prices. We go there for meals and the food is pretty pricey so the rooms might be as well. You could always try the Hotel Cornavin which is not great but since its right near the main train and bus station makes transportation easy. If your looking for a hotel near Contrin airport there is the Hotel Penta or Movenpick (good ice cream) I think the Hotel du Rhone would probably be either booked or too expensive. If you need to stay in France there is a Holliday Inn near Thoiry.

Hope this helps, post again if you require more specifics about any of the hotels I required or any other Geneva questions. I do spend about 3 months out of the year in Geneva, and am there now.