Overnight to Bosnia or Day trips

Mostar is surely the most common side trip into Bosnia from Croatia. It's a nice town, easy to get to by car or public transportation, not too big. I spent a night but that was years ago. It makes quite a contrast to the "sunny coast vacation town" destinations in Croatia. Mostar is roughly half Muslim, half Croat (Catholic). If you visit, do read up on the Bosnian war - a lot of heavy, bitter fighting took place in Mostar, and the famous old bridge was blown up - and later reconstructed.

I understand Mostar has become much more touristy especially in the day time (tour groups) in the last few years but is much quieter at night.

If you have more time, Sarajevo is a more significant city than little Mostar, but it is a bigger time commitment - and more time to get to/from.

In Dubrovnik, I would try to stay in or close to the old town, easier if you don't have a car. If you want to rent a car, rent it as you leave Dubrovnik - it's a bit of a hassle having one there. But driving in Croatia and Bosnia is pretty easy.

Forgot to mention I have two kids with me. I will indeed have a car with me. At the moment I am wondering if visit to Bosnian wineries is worth the trip.

For example Tvrdos Monastery.