We have 4 days between cities next week. We want to spend 2 or 3 days in an ancient small town/rural village (off the beaten path)in the Czech Republic (northern or eastern) or Poland (western or southern).
Get a map of CR or Poland and find the villages you want to visit in the area you choose. Then search for sights at each village and read about them.
Have you arranged a rental car, or have you scoped out the public transportation in Poland and CR?
The area may be a bit too far to the east, but in far southern Poland in the foothills of the Tatras/Carapathian(Karpaty) mountains there are some really charming little spa towns. Don't be put off by that, the only tourists there are Poles from that region. The towns are: Nowy Sacz, Stary Sacz,and Krynica. I never got the chance to visit them, but I passed through the area on my way to a park where a Polish friend had roped me into participating in a paintball tournament.(Long story:-) ) Anyway it was an absolutely gorgeous drive and my friend told me all about these great little spa towns.
Also in southern Poland is Zakopane which is quite touristy, but there are some amazing villages nearby where they have preserved a lot of traditional regional architecture. These include Chocholow, Zubrzyca Gorna and Orawka.
Whatever you decide, have a great time!