We will be in Kotor in late September and plan to go on to Mostar for a few days. We won't need a car in either city. For me, it's a hassle and expensive to rent a car for a day or two, with extra drop-off charges in another country. Has anyone had recent experience with a private car and driver for this route? I've looked at Dubrovnik Riviera Tours and Mont Travelers, but am looking to hear from someone with personal experience with either of these companies, or with someone else.
Not specifically on that route, but we had a fine experience with Dubrovnik Riviera Tours on the Peljesac Peninsula.
Ermin Elezovic, email@example.com is a wonderful driver and guide, based in Mostar. I hired him to do a day trip/transfer from Mostar to Sarajevo in 2018 and it was a fabulous, amazing day. I understand that Ermin (or a wonderful young man who works with him) also will pick up in Dubrovnik for transfer to Mostar and other points in BiH. You'll need to ask him if he can pick up in Kotor. He is recommended by RS and his contact info is also in the RS "Croatia/Slovenia" book in the chapter about Bosnia Herzegovina. And while I'm at it, Ermin's wife, Alma Elezovic, does private guided walking tours of Mostar, and she is wonderful! Her contact info is also in RS's Croatia/Slovenia book.