+1 for a trip to Gydnia if you go to Gdansk. A lot of money has been pumped in there and it's quite up and coming for Poland. Lots of nice bars and restaurants, especially good if you get good weather.
Also, if visiting Auschwitz I would recommend planning very little that evening i.e. don't go booking a nice restaurant or planning a bar crawl. It's a good experience but afterwards you're likely to just want to take it easy and not be in mood for enjoying yourself.