Some general tips for looking at hotels in Europe:
-Air conditioning is not a given. Assure it’s available in the hotel if you’ll want it during warmer months.
-Similarly, elevators. Though their absence is less common, and usually limited to rather small hotels at the lower end of the budget scale.
Location:
-I prefer not to stay if the very heart of tourist action, but rather in a neighborhood where real people love their real lives. For convenience, this usually means the residential areas closest to the center. (Don’t overcorrect and end up at a hotel in business district that’s dead off-hours.)
-How I’m traveling into and out of the city might influence location. Especially when that means I want to stay within walking distance to a train station.