That's a fairly rigorous schedule with two children. We did 21 days with two 12 yr. olds and the best part of our traveling was bivouacking for a few days at a time at locations where the kids could do kid stuff like swimming, miniature golf, and other amusements. They got bored fast with usual adult interests.
We traveled by train with First Class Euro passes and, in hindsight, that was a good choice. No worries about navigation, parking, and care of the vehicle. The great thing about unlimited train fare is that if you don't like a particular location, the trains are ready to take you to another.