Colmar and Alsace

I enjoyed Basel very much. I especially enjoyed the Marketplatz and Rathuis and the Munster. Be sure to look behind the Munster for a river view. Also we crossed over the Rhine on the Wettsteinbrukke and walked along the river to the Mittlererheinbrukke and crossed back into the old town. We enjoyed the beer hall on Freiestrasse and Barfussergasse next to the McDonalds.
We stayed in Colmar for just one night, but it was a BnB in the middle of the old town called Maison Martin Jund that had a working winery. I recommend a stop there. If you haven't made your reservations for Colmar, this was a delightful, quirky and inexpensive place to stay. We stayed at BnB at another winery in Eguisheim. Their tasting room was right below our lovely room. The winery was called Ginglinger and the BnB name was Hameau d'Eguisheim. We enjoyed driving the wine route (Route des vins Alsace) we loved the little wine towns including Eguisheim, Ribeauville, Kayersburg and Riquewihr. We went up to the Castle Haut-Koenigsbourg. I have not been to Zurich. I've heard its rather large and doesn't have the charm of other Swiss towns.

For a day trip from Strasbourg I chose Basel over Zurich because of the fabulous art museum and its collection of Böcklins. Depends on your interest.

With a car, I'd recommend staying in Eguisheim or one of the other villages. If you stay in central Colmar, you'll have to drive through the city in and out every day. Are you going to be in Strasbourg? If that's not part of your itinerary, I'd recommend that as a day trip (better as an overnight or two) rather than a Swiss city.

I enjoyed all the Alsatian villages. If you like animals, you will enjoy interacting with the Barbary apes at Monkey Mountain - near the Château du Haut-Kœnigsbourg, also worth a visit.