Bosnia, Croatia, Montenegro Itinerary Help!

I can only comment on the Mostar-Dubrovnik-Kotor part of your trip. One night in Mostar was enough for us. You can see the old part of town, the bridge, visit a mosque and climb a minaret and have a couple of good, inexpensive meals. I think you have plenty of time in Dubrovnik. We drove to Kotor, so we saw the sights on the way there and back (returned our rental at the Dubrovnik airport). Once we were in Kotor, we didn't touch the car again and instead filled our time walking around town, climbing the walls above town twice (once in the afternoon and again the next morning to take pictures with better light.) Later that day we took a boat from Kotor to Perast and back. We had a nice lunch in Perast and the boat ride was great. I would recommend spending your time hiking or on the water rather than driving around. You should find plenty to do and we found the driving around Kotor to be a bit more "white-knuckled" than most of the rest of our trip through Slovenia, Croatia, Bosnia-Herzegovina and Montenegro.

I think give the time you have available, you've put together about as good an itinerary as possible. Personally, I'd suggest one more night in Sarajevo and one less in Dubrovnik, but it depends on what you like to see and do. Also, you don't mention when you're going. If it's in summer, you'll find plenty of options for your excursion to Mljet, but be aware that schedules are reduced significantly in the off-season.

It looks like an amazing trip! You're going to get to see a lot in 10 days. Enjoy!

If you had another day or two in Kotor I would agree with renting a car. But, with only one day, you have to choose, and the drive around the bay or up to the mountains will take a day. And, the person driving will be 100% eyes front- very tortuous roads. And, speed traps! You get nabbed, you'll be in court the next day, not going anywhere. For one full day consider doing without the car. You can do a nice trip on the Bay with a British couple who live on their small sailboat (Look up Yacht Monty B). They book up far in advance but have cancellations. Hard to beat the day you will have with them on the water. Oh, and be aware Kotor is rainy. Have your raincoat handy.