Spending a week in Germany and using Frankfurt as a base. What are some of your favorite daytrips? How would you spend that week?
To start with, consider the Mittelrhein (Bacharach, St. Goar, Koblenz)
There are lots of possibilities, with the Rhein of course being near the top. May I suggest Heidelberg, Würzberg, or even Cologne. Also nearby is Bad Homburg which has a lot of things to see, though it is isn't in Ricks book. There is Hessen Park which is an Open Air museum, the Saalburg - a reconstructed Roman fort that was once there, the palace/residence of Kaiser Wilhelm and it is all located in the Taunus mountains which is very pretty. I don't knwo when you are going, but there are any number of events going on all over the Rhein/Main area. Jousting tournaments, Jazz festivals, medieval markets, wine fests, art markets, street festivals, and so on. If you let us know when you will be in Frankfurt, I can send you a list.
Also the middle Rhein first... then more to the north, I like Fritzlar (birthplace of the Germany Empire, Thor's Oak, nice Marktplatz and more)www.fritzlar.de and Büdingen (nice little Altstadt, medieval wall and memories for this Army Brat). www.stadt-buedingen.de
I was near Frankfurt for work and took day trips on weekends. My personal favourite was Baden-Baden. It was such a relaxing place. The Bathhouse was great. I also went to Cologne by train and took the boat back, stopping at some castles. I wasn't too impressed by castles. Well, I was never interested in castles to begin with, but some people might find them very interesting. I also like Heidelberg, although Rick Steves advised against it. I think it's still worthy of a day trip, but expect to see a lot of tourists coming in big tour buses.