Gengenbach Hotels/Pensions

The following places are not personal recommendations, just places I'm aware of within walking distance of the train station and that you may not have found on the standard booking engines:

Bigtyke stayed in this apartment recently; see second link for his trip report and comments on the apt.:

Ferienwohnung Wink
Bigtyke

Two other places:

Kienzler apartment

Ferienwohnung Moser

I've not stayed at either, Alexandra, but absolutely LOVE the Die Reichsstadt. While the website is only in German (you can use Chrome to make it into English) all the staff are perfect with English. I hope it is not out of your price range. The best deals there are in their package deals, and the food is top notch, and eating in the garden is romantic and fun. Less than 5 minutes walk to the station and right in the middle of the town.

Bigtyke here.

I really liked the fewo we stayed at in Gengenbach. Only a short walk from the train station and right on the main square in the old town. Price is right. No breakfast but plenty of places right out the door if you don't want to fix your own.

We loved the Pfeffer und Salz hotel-restaurant. It's about a mile outside of town in a beautiful rural setting. Also, the staff is great: one day the manager drove us to the train station in her own car. One caution, however - it's on the side of a hill and you have to do a lot of climbing to get to the rooms. If you're young and healthy, that's not a problem; but if you have mobility problems, then you might want to look elsewhere.