Me and the wife will fly into FRA in Aug. From there we rent a car and drive to Berlin for 2 nights, then Prague for 2 nights, then Vienna for 2 nights, then Innsbruk,Austria for 1 night, then Mullhouse,Fr for 2 nights, then Luxemburg for 2 nights, then Amsterdam for 2 nights and back to FRA for 2 nights. We plan on visiting about 8-10 castles on the way. We like the car because it affords us the ability to divert off the path for last minute sights.