Forget about flying within Poland unless you're trying to launder money. The trains are pretty good and where they don't go the buses do. As well as the plodding government service, private bus companies undercut each other viciously on many intercity routes. Driving your own vehicle around Poland is by far the most convenient option, but don't bring your spiffing new Jaguar, even if you forewent the walnut trim: it's gonna get ripped off. Fill up your tank every time you see a petrol station and carry some spare thingummy ratchets and dooveywacker belts otherwise you'll be waiting around a couple of weeks for them to arrive from Germany. Rural Poland is quite conducive to cycle touring, being mostly flat and relatively quiet, but the urban areas are bike-unfriendly with few dedicated paths and many hostile motorists.