Suzy,
You might have a look at Hotel Walhalla which is about three minute walk from the main station (Hbf). I found the rooms to be very modern and comfortable and the staff are great. It's also a very convenient location for embarking on local tours, as the tours depart from the lot across the street from the hotel. I booked some local tours while there, and the desk clerk came with me and make all the arrangements, which was very helpful (of course I can't say whether all guests get that same level of service). There's also a Tram stop right outside the front door, and the entrance to the Rail City is about a 30 second walk and then down some stairs.