The Hotel Leon advertises itself as something between a hostel and a small hotel. In truth, it’s actually much nicer than a standard hostel (no dorms, but rooms with up to four beds and private or shared bathrooms) and not much more expensive. The rooms are basic but quiet and clean.
If noise is an issue, ask for a quieter room overlooking the back garden. It’s one tram stop (Ortenovo náměstí) from the Nádraží Holešovice train and metro station.