Why go to Prague?
A 10 mile taxi ride from the airport lies the Vitava river. It is broad and peaceful and following it slowly north on foot is a pleasant way to get off the beaten track. It's a bohemian style walk through actual Bohemia. You can take a bus back into the city or to the airport from Kralupy nad Vltavou. It makes the initial taxi ride somewhat longer, but crossing over to walk on the east side of the river will give you a quieter hike. You'll probably meet a few curious fishermen peacefully watching the world go by who are interested to chat with you. They won't be used to seeing tourists out here. And that is a good thing.