I stayed at the Sheraton over spring break 3 years ago and loved it despite it being a ways out of town. We didn’t have a car, but we managed to make it work with the public bus system although I was always quite nervous about missing the stop, as at that point stops are very far apart and busses only come by once or twice an hour (can’t remember exactly). We went into the city a couple days and to Hallstatt to the salt mine another. I don’t think there was a good option, at least not on points, in Salzburg at the time, so if there is now I’d do that for exploring the city and the Sheraton for a couple nights to enjoy the mountains and lakes.