Forget everything you know about driveways. Asphalt, concrete, crusher run gravel, rail road ballast, paving stones... If you have a long driveway, or if you need a system of driveways on a farm, and you are planning to go with those common methods of paving a driveway, you are going to need a separate mortgage just for the driveway (or driveways).
Stacked stone spheres and garden sculptures, by Devin Devine.. I should maybe also add that using the above system I have never once had a single flagstone patio fail. Okay, maybe one stone with some minor settling—fixable in a few minutes (and rare, very rare that ever happens) but never any major problems.