We're staying in Dubrovnik, but we'll have a car. Should we drive to Mostar for an overnight visit? Our AirBnB has parking.
Obviously, I know we would be able to stop other places along the way, but we won't need the car while we're there. Are there disadvantages to taking the bus?
If you are planning on staying the night either way, then it will likely only depend on the bus schedule.
If you have the car anyway, I would certainly take advantage of it--I have read about some nice places en route in Hercegovina, like Kravica waterfalls, Blagaj monastery. See http://www.bhtourism.ba/eng/whattodo.wbsp
Buses are inflexible. Cars are flexible.
Of course, Mostar is Bosnia-Herzogovenia, Dubrovnik is Croatia. Make sure if you take the car that you can to go B-H. If you do drive, you could also go to Positalj, an amazing stone village 30 KM from Mostar, and worth an hour or two.