Venice: Ca' Badoer, in San Polo, easily reached from San Toma vaporetto stop and 5-minute walk. 10 minutes to Piazzale Roma, 15 to Rialto (shorter if you don't stop and shop and eat gelato along the way, ;). http://www.cabadoer-veniceflat.it/ FABULOUS and wonderful Ketty. Very reasonable--70 EUR/night in June & July; no breakfast but kitchen, bath, sitting area, washing machine! Tiny but functional lift. Good AC.
Florence: Soggiorno Battistero, http://www.soggiornobattistero.it/, absolutely perfect location, great breakfasts, RIGHT on Piazza San Giovanni (the piazza in front of the Duomo and the Baptistery). Kelly and Luca. They are the hardest-working young people in Florence. On the 3rd (American 4th) floor, but there is a large and modern lift! Three of us stayed for 140 EUR/night. Good AC.
Siena: Alma Domus. http://www.hotelalmadomus.it/ Louis and his lovely wife. STAY HERE! I would stay for a month if I could. Great breakfast, great location, absolutely the best view in Siena. Did I mention I want to move in and stay forever? We had the biggest, most beautiful room--number 5. 125 EUR/night. Great shower, great AC, perfection.
Rome: Hotel Rosetta. http://www.rosettahotel.com/ 5 minutes walk to the Forum or the Colosseum. No breakfast, but great shower, quiet courtyard room, wonderful Francesca. 120 EUR. Great AC.
I'd stay at all of them again!!