There isn't a website that you can check availability of cat. 1-3 but if you go to any of the travel sites (expedia, travelocity, etc) and go through the motions of booking, you will get a pretty good idea of what's available. Most sites return a maximum of 8 rooms in the selected category. Make sure that you put the correct number of people in each room as they may show availability for 2 people but not 3 or 4 in the same category.