croatia route and time management

I think around 3 days in each place works well, and connections are good so you can move on as you wish. I haven't been to Sarajevo, so maybe you'll et some good advice on how much time to spend there.
Re route: check around on bus schedules to see which works out better:
Dbv-Sarajevo-Split-Hvar-Zagreb
OR
Dbv-Hvar (via ferry, maybe stop at Korcula on the way)-Split-Sarajevo-Zagreb
You might want to stop in Mostar for one night (after Dubrovnik or after Sarajevo)
you might want to stop at Plitvice Lakes National Park en route to Zagreb, either an overnight or just a few hours.
One caveat, Hvar might be pretty crazy in August--there are many many options near Split. I imagine most of the coast is pretty crowded at this time of year though.

I think that rout

Dubrovnik - Hvar - Split - Sarajevo - Zagreb is more better

Greetings,
Just spent three weeks in Croatia. Loved the islands and smaller towns-- grew impatient in the cities.
We started in Zagreb, enjoyed it, but, if doing it again, would sacrifice it for more coastal time.
Dubrovnik was definitely cool as was Trogir. Split was too big and, other than the Diocletian Palace, just another city.
I agree that Plitvice NP is very worthwhile and a good addition.

I think that if UNESCO recognizes a location, that is probably a good indication that it is worth visiting.

I f you get to Hvar you should stay in Vrboska. I've been all over Croatia on two trips(going again in July!) and this village is a paradise. It's large enough to have a number of restaurants and cafes and good night life but it avoids the hordes of tourists that descend on Havr town. It's the most scenic town on the island. Check out pictures on Google Images and then do a Google search for more info. and you'll understand why I recommend it. Once you see it you'll want to stay as long as possible. Check out the Villa Welcome on the internet. It's one of the cheapest private accommodation and the owner and location are great. Enjoy Hvar!