Krakow is a great place to visit because there is a simple tourist trend that hardly any foreign visitor ventures out of the old town 'market square' part of the town, and within 40 minutes walking distance there are loads of interesting historical and cultural places to visit, which admittedly do have a lot of tourists in the holiday season, but mostly polish ones.
Also get away from the tourist traps and food and drink is good value. Locals do get fucked off with stag group dicks, but there is not that many compared to normal tourists.
Riga .. in a way i sort of liked visiting there, the old town is mostly full of foreign nob heads and organised crime though and the police are wankers. So for any visit there a bit of research is required on where the wankers go, once you know where the wankers go just avoid those places like the plague. Latvia has been hit hard by the recession though.
Tallin is a nice place to visit, the estonians freak me out a bit though for some reason but the russian estonians are a bit more normal, why i have this stupid impression about the estonian estonians i dont know, perhaps it is the weird language.