gdansk has a beautiful old townhttps://polishforums.com/travel/poland-hometown-vacation-pictures-1066/4/
close to shops, various shopping centres, theatres, cinemas, bars and restaurants. the main street is pedestrianised and starts at the top of the old town, about a 5-1O min walk from Zakopianska, and runs down to a canal at the bottom with gates at both ends - see pictures in link above.
the old town is a mix of old and young with an emphasis on old if anything. loads of tourists, especially in the summer when they have various events including a huge market that takes over pretty much the whole of the old town.
i dont really know much about brzezno other than it has a beach and a pier... it is near the nowy port part of gdansk which is full of ugly communist blocks but also a part of the city ear-marked for huge regeneration... at some point in the future... when they get round to it...
this site will give you an idea of what property is being sold for
partnerzy.gda.pl - it has an english version
search under gdansk brzezno and gdansk siedlce