Any fun things to do with teenagers?
Cycling around parts of the lake then take the bike onto the ferry (for example friedrichshafen to Bregenz), meersburg castle , Konstanz has a great center, etc -
Our teens pretty much like what we do tho! Bodensee is beautiful - but we have family there so we visit with an added purpose.
Maybe visiting the Zeppelin museum (https://www.zeppelin-museum.de/en) or the sunken stone age village (https://www.bodensee.eu/en/what-to-do/map-of-lake-constance/lake-dwelling-museum-unteruhldingen_poi160) would be something.
The first time I experienced Lake Constance, I was on a HS trip. We visited the Rheinfalls and the Island of Mainau. Mainau is a botanical garden, and has some incredible flowers and it is on the lake so some really great views.
As an engineer, I found the Zeppelin museum absolutely fascinating.
I love the town of Lindau. I've visited it as a day trip from the Oberallgäu multiple times and spent four nights there in 2017.