Depends where you are. We just got back from a big trip yesterday, and paid :
Budapest, 1 bedroom apartment, ~$40/night
Vienna, 1 bedroom apartment, ~$50/night
Zurich, hotel, ~$120/night
Paris, very nice 1 bedroom apartment (chandeliers and stuff), ~$115/night (this was an expensive last minute fix to a serious problem - we rented a place on AirBnB that turned out to be a HUGE lemon and had to find a new place to stay on the spot at 10PM, in the middle of a rainstorm, with limited French speaking abilities, and no phone - fortunately we've been to Paris before and are familiar with neighbourhoods and stuff)
I really don't like to pay more than $100/night, and prefer closer to $50, but it's a bit of a stretch in some European cities.