Lived there for 17 years before I couldn't take the summers any more. Great in the winter with overnight hours usually around freezing and daytime highs in the 50s or 60s. You will need a car to see the natural sights around the city but they are worth it. Saguaro National Monument, Sabino Canyon, and the Arizona-Sonora Desert Museum are all worth the drives and offer good walking opportunities.
For lodging, the Hotel Congress downtown (http://hotelcongress.com/
) is a nice old building with a nightclub and dining on the first floor. Noisy but I always enjoyed evenings out there. It has been a decade but there was a lot of good dining nearby as well when I left.