Since Poland has developed primarily as a city break destination, there is little in the way of an internal flight network to get you around, and as such, if you want to make an extensive tour of the country, then your best bet is to hire a car, and make your own arrangements as you go. Because petrol stations are few and far between when you get off the beaten track, it pays to fill up with petrol every time you pass a garage, rather than risking a long walk with an empty can.
Within the cities, the public transport is very good. Government taxis are metered, while private ones will agree a price before you set off.