What are the chances of booking a hotel in Tuscany without prior reservations? I don't know as yet which cities I will visit, so I have not made any reservations. Do you recommend going without reservations?
Also, how can I get a bus schedule for Tuscany?

Depends a lot on the time of year, the part of Tuscany, if you can use the telephone in Italian and how picky you are (like having A/C). I saw folks get rooms in July one year by asking at the tourist bureau in Greve- but without a car you are very limited in some of the small towns-sometimes a place a mile out of town is a long, hot uphill walk. In Florence you just start knocking on doors on Via Faenza for cheap rooms. There are many bus and train lines depending on where you are going. Google autobus and start translating. I am not a risktaker anymore and troll all these sites and send out lots of emails in order to make sure I will be staying at pleasant places.

Hi,
Three of us traveled through Tuscany without reservations and did not have any problems getting a hotel room. We were there in the beginning of July and traveled for about 10 days. We did have a car. In the Chianti region we stayed at a wonderful villa with a view and a pool. In Todi we stayed at a B&B with a view to die for, although I know that technically Todi is not in Tuscany. In Florence you probably need a reservation. We stayed in Lucca and found a nice little place in the town center. I wanted to travel without a strick plan and it was great, but not for everyone.

Traveling in Tuscany in June without reservations may be difficult. You will need to spend time you should be touring and enjoying the scenery and the food and wine looking for a place to stay. June is a prime time and the place will be crowded. Major cities will be particulaly difficult. A little planning can be fun and even if it's not it will pay dividends.

My wife and I stay in the San Gimignano area every June. We found our great hotel by just driving around the area. We stay at the Hotel Sovestro. It's about two Km out of San Gimignano, and it has a great restaurant. It is VERY quiet, tucked away in olive groves and vineyards. It will cost about 98 euros per night. We've found that San Gimignano is a great place to base from for exploring Tuscany.