Neither Baden-Baden nor Freiburg have much to do with the Black Forest despite their inclusion under Rick's Black Forest listings.
"Major attractions" invite a certain level of tourism. The impressive Vogtsbauernhof open air museum in Gutach, in the Kinzig River Valley, can be reached easily from a fair number of nice towns. Most recently I stayed at a farmhouse apartment in neary Steinach - very nice. Look into the other Kinzig River Valley towns between and including Gengenbach and Freudenstadt for plaes to stay also:
Gengenbach and Schiltach might be the most attractive of these towns, but you can't really go wrong here. Other attractions nearby include the summer bobsled in Gutach, the Triberg waterfall and Black Forest museum, the Costume Museum and Gedenkstätte Vulkan memorial site in Haslach (site of a former Nazi work camp), the Fasnacht Museum in Gengenbach, and the Alpirsbach Brewery are other good options.
Further south... I spent about 5 nights a bit more than 10 years ago in Loeffingen, a handsome town near the Wutachschlucht Gorge (popular with hikers) and not far from Donaueschingen (the source of the Danube.) I took day trips from there, one of which took me to Neustadt, near Titisee, where I hiked through forest to a nearby peak called the Hochfirst with a hikers inn and a lookout tower that offered stunning views of Titisee Lake and the Feldberg Mountain (highest point in the Black Forest.)
You might visit the Rothaus Brewery too. It's in Grafenhausen.
I realize you have a car, but I'm giving you a link I have which contains a "KONUS" map showing towns, roads and railways in the Black Forest. As the trains can be used free of charge when you book in certain towns, you may want to try them. Both the Black Forest Railway (Offenburg > Donaueschingen) and the Hell's Valley Railway (Donaueschingen > Loeffingen > Freiburg) are among Germany's most scenic train rides - and you can enjoy the scenery traffic-free:
I've used the KONUS program extensively for my day trips around the Black Forest, with great success.