Being a national park, Banff has plenty of accommodation. However book early, because places fill up quickly both in winter and summer. Note that in order to live in Banff, as opposed to being a perpetual tourist, residents must have a business in town. If you have access to a car another, and often cheaper, alternative is to stay in Canmore and drive to the ski resorts or in to Banff.
Most hotels are located along Banff Avenue or on Tunnel Mountain Road.