[Kool Kat]

Planning a trip (sometime between Apr and Jul) to hit those 3 cities via rental car once we fly into Europe from Texas. What I'm trying to figure out is which city is best to fly in and out of in terms of ease, cost, convenience, congestion, time of year, driving, etc. We'll stay in each for 3 days or so. We could either use one city as home base and fly in/out or fly into one, get rental car, then drop off/fly out of a different city/country, which might be complicated. Anyone with experience that can share thoughts?