best way to start in Dubrovnik and go north up the coast?

Island hop! Stay in Hvar or Korčula, then Split for a night or two.

Island hop if you have the time for it (sounds like you do).

Don't island hop if you are travelling between the end of September and late April - too much of an off season feel with many restaurants etc closed, a reduced ferry service and a greater chance of them being cancelled through bad weather.

Do you have to go back to Dubrovnik? You could cover Vis, Mostar etc from there.

I am going up the Coast around Sept 20th ...Dubrovnik-Korcula-Split ...I looked at the Ferry schedules and they seem to be running almost every day ....would much rather go by ferry than bus!

Thanks everyone!
We do not have to go back to Dubrovnik.

My wife and I made the bus trip from Dubrovniik to Split last May 2014. What a mistake! The ferry wasn't operating so we were stuck with the bus. If I had it to do all over again, I'd rent a car instead of the bus trip.