Fly Frankfurt rt. Rent a car. Go south on the expressway and cross into France just North of Strasbourg to the Route de Vin Alsace (after more than 500 days as EU tourists, this is where we keep going back to), And I've got to recommend the restaurant Au Lion de Or, still owned and operated by the founding family in the original building. First open for business 3 years before George Washington was born. Generally avoid big cites-- no fun driving there, but do go into Colmar. Continue south on the expressways to one of these: 1] Switzerland , where you will have to buy an outrageously expensive window sticker driving permit, to the Lauterbrunnen Valley area & the 3 Passes road tour. If bad weather, cut across the Black Forest to the N shore of Lake Constance to the German Alpine road to Fussen (the Royal Castles) then the Romantic Road to Wurzburg to Heidelberg (we always swing by Schwabisch Hall) to the Rhine & Mosel Valley and back to Frankfurt (probably too much, but you get the idea)
2| French Alps instead of Swiss Alps. Again, only in good weather. Return toward Frankfurt via Dijon, Burgundy, Rhiems, maybe by the stunning Mosel Valley if enough time.
The Black Forest reminds us of the Appalachian Mtns with worse roads. The Alps are a way better bet for scenery, and for quaint villages, Alsace, Lake Constance, The Romantic Road etc & The Mosel Valley blow the Black Forest out of the water. If you want to drive around rolling hills pretending to be mountains, better to go into the Vosges in Alsace where the food is better.
Essential for a road trip (and for EU travel in general): The Michelin Green Guide for each country. The Michelin Guide will fill you in on lots of stuff to see along all these general routes.
Food: Alsace is next to Paris as foodie paradise. . German food is almost as good as French but we have never been fond of bland Swiss food.
Wine: Oddly, try beer in Alsace. We once bought 21 cases of our favorite French wine. Last year, the current vintage was selling for $3,800 a bottle. When we bought the 21 cases in the 1970s, it was $7 a bottle (took us 20 years to drink all of it. I wish I had a case left for resale). The point is that globalization made the price of fine French wine go nuts. You can bet the French don't drink in. The French drink house wine at $10-16 per liter. So should you. Excepting pinot noir, CA wines are as good or better than French wines and a lot cheaper, but where EU wines excel is in the jug wine market-- vin de table, vin de maison.
In Alsace & especially in the Mosel Valley if you get there, it would be worth ordering a low priced bottle of Gewurtztraminier.
BTW: don't drink and drive in the EU. Not a problem bechances wine/beer is sold everywhere within walking distance of where you are.
In Germany or Switzerland, try dunkle bier (dark beer). We ordered dunkle bier at a restaurant in Austria. The waiter said, "Americans don't like dunkle bier". I said, "we do", and I think we made a friend for life.
