While in Germany, I almost always stayed in Wiesbaden, which is not far from the Frankfort airport, and reasonably close to Rüsselsheim where I worked during the week.
Wiesbaden is a beautiful old town, full of
"old" money. One of the ways to lose that money is the
Kurhaus, or Casino.
The Kurhaus is located in a wonderful park
along Wilhelm Strasse.