We are planning a trip in May and using Rick Steves guide books. We attempted to book rooms in his highly recommended hotels and have been told they are already booked. Have we started too late or is it too early for the hotels to confirm?
Don't worry, just keep looking. I didn't think May would be so hard either, but we have definitely had a lot of people tell us they are booked! I have just had to check with a lot of hotels. In Siena, we found a room at Il Chiostro Del Carmine after trying a few.
You will still be able to find great places to stay, even if they are not in the Rick Steves book. If the Rick Steves hotels are full, try tripadvisor.com, Lonely Planet, or Rough Guide for other hotels.
It used to be that you could just show up in a town and call one of the recommended places in the Rick Steves book and get a room. Now, there are so many people using his books that a lot of his hotels are booked in advance. I'm kind of a last minute planner so I almost never am able to get a room at one of the RS places. I tend to get most of my hotel recommendations from tripadvisor ... and in general, I've been very happy with what I've found.
We stayed at the Cavallino D'Oro hotel in Castelrotto last June. 44euros/pp, including a buffet breakfast with a large array of choices. The room was good-sized, very clean and had a large, modern bathroom. The restaurant serves a nice dinner, and some nights there is live music in the bar. The staff were all very friendly and helpful. Oh, and they answered our booking request very promptly.
They are probably booked. Assuming you've tried the hotel directly, you could also try alternative booking engines (e.g., Venere.com, Orbitz) as some of the places open reservations specifically for those services. Browse this site, especially the guidebook feedback section, there are other traveller recommended hotels listed under best/worst accommodations. Trip advisor is pretty reliable. People on this site are also super friendly if you post specific questions.
PS It's possible that there are Rick Steves tours staying at some of the hotels, causing them to be full. He has many, many tours going on during May (when I was on the 17day best of Italy tour, there were at least 3 RS tour groups in Venice at the same time - ours, a Venice/Florence/Rome, and a Best of Europe)