somwhere cheap and fairly central, I guess.
I would recommend staying central, so you will have an access to public transport - the trams in particular. Taxis are a way to go really and they are fairly inexpensive. It all depends on your budget really. I don't really know where the hostels are located in Szczecin and if this is where you want to say in the first place.
But I can recommend a very nice tea/coffee place run by a friend of mine, which is downtown and close to the transport system:)