Wroclaw
As always, a city which has been beautifully restored following WW2. Wroclaw is rapidly becoming a big tourist spot, with prices to follow. Accomodation is expensive and hostels are limited still, but this will probably improve over time. At the moment I couldn't find any hostels with a decent location in the old town, although there are a couple close by the train station, which is convenient for arrivals and departures.
I stayed at the MDK centre one night (very cheap, very basic and very annoying that you have to be out between 10am and 5pm each day). Across the road is the vastly more expensive, but also much nicer Stranger Hostel, which has free breakfast, free movies, free internet, free coffee and generally friendly staff. Still, it's a little cramped and not the best value around at 50 zloty per night, 55 on weekend nights.
There really isn't so much to do, other than wander the Rynek and old town, sitting in the cafes and drinking beer. Which isn't that bad, when all is said and done :)