Single person for one night only, can you recommend any?

If it were me I'd go to the www.hotel.de website and look for a 3-star,
though a two-star may still be just fine--I've never been dissatisfied by
picking one simply by price and location on that site (usually choosing
location by looking at the little railroad icon and seeing how far the hotel
is from the train station, and then maybe clicking for more detail about the
hotel--and the prices tend to be hard to beat).