Freiburg or nearby for 2 Nights?

what sort of an experience do you want to have. By smaller, how small? Freiburg im Breisgau is a fairly large city, like Bern.

My suggestion would be Gengenbach, which is about a 40-minute train ride from Strasbourg, and it's just a wonderful place to stay. The town is lovely with beautiful half-timbered houses (it's frequently called a "chocolate box" village) and has a charming Altstadt, with quite a few restaurants and cafes to choose from. And for its size, it has a decent amount of hotels. Gengenbach makes a good base as it is right on the main train line, and gives you the options of some interesting day trips, and also makes it very easy to get to Strasbourg.

One nice benefit if you stay there is that you receive a KONUS card, which entitles you to free public transport throughout much of the Black Forest region (you don't get that same benefit in Freiburg). There are many charming villages in the region that you can visit along the Black Forest Railway, and there is also the Vogtsbauernhof (open-air museum) that is a joy to visit and easily accessible by train.

The town church (Saint Marion) is quite beautiful, and the medieval gates to the city are really interesting. The Benedictine Abbey is also worth a visit, and behind it are some cloistered gardens that were lovely to wander through. This was one of my favorite places. It was peaceful and inviting and I could have stayed for hours. There were little signs of inspiration scattered around, and some children from a nearby kindergarten playing on one side.

Also don't miss a walk through Engelgasse and Höllengasse streets (near the TIC). Here you will find cobblestones and half-timbered houses, flower pots and cats resting on doormats and quaint dolls in the window. I felt like I had walked back in time when I strolled through these quaint and narrow streets. There is also a nice hike you can take that will get you above the town with some absolutely beautiful views of below. The hike ends up at a church called St. Jakob auf dem Bergle that sits above town. The TIC in town will have maps showing you how to get there. it was a really nice hike and as I said, the views are just lovely!

Gengenbach is a really good choice for all the reasons mardee has provided.

Additionally, the KONUS card, which is valid on your day of departure from Gengenbach, will provide you with free rail travel as far as the border town of Kehl. For the Kehl to Strasbourg leg, a special cross-border ticket - the Europass 24h mini - is available to cover two adults; buy it online, on the DB app, or at the train station from a ticket machine in Gengenbach for Kehl > Strasbourg:

https://www.cts-strasbourg.eu/en/buy/our-tickets/occasional-tickets/europass-mini-24h/

The same train that takes you to Kehl will continue on to Strasbourg - you just stay seated on the train and show your ticket if asked.

Personally I like Freiburg. The Kunst (Art) museum is very nice, and the Archeology Museum has a really good prehistoric to Celtic collection. Plus I've had some very good meals in that city.