What would be a great city to visit in the Black Forest that is great for shopping and sight seeing
Freiburg - check out the city's website:
Titisee, big pedestrain zone with lots of shops for the tourists. It's a medium sized town on a beautiful lake in the middle of the Black Forest.
We spent a few days in the Black Forest and did a day trip to Lake Titisee. It was a fun day. Some in our group hiked around the lake. Others rented row boats and paddle boats. There was some shopping. It is a beautiful place, but I would not consider it to be a city, nor would I say it would be good for shopping or sightseeing per say. If you are looking for nature it would be a nice choice.
My favorite place in the Black Forest is Bad Herrenalb, in the north, a little town 45 min by streetcar from Karlsruhe, very scenic, but not much for shopping. Next favorite is Freudenstadt, an S-Bahn trip up the Murg river from Baden-Baden. It has a 700' square market place surrounded by a cover arcade (2800') with shops and restaurants.