I love Sarajevo. I will be back in September.
The Sarajevo to Mostar train looks interesting and convenient (https://www.seat61.com/trains-and-routes/sarajevo-to-mostar-by-train.htm) but awrzesinski, is correct about private transfers in BiH. One of the advantages to travel in BiH, Montenegro, Albania, N. Macedonia is that you can either do a less expensive tour .... or, you can do a better tour for the same price. Whats better than a driver for the day? "Pull over here, I want a photo", "what is that", "have you been to .......", "lets stop for some road food"; its great.
I go into the area every year, this year I think twice (BiH once and Montenegro once). Despite that I still dont try and plan it alone. I call this lady: Dijana Krkotic, Doclea Travel, whatsapp/phone +382 69 277 749 [email protected] www.docleatravel.com
I turned over my May fishing trip (Montenegro) to her and so far she got me a better room at a better price on the coast. She set up the transfer from the airport to the fishing hotel in the mountains, which is a 3.5 hour trip but we have some stops planned along the way. For the trip back to the coast she found the perfect winery and olive orchard to visit.
The point is, if you want to see the places inbetween they are worth it in that part of the world and a driver makes it possible.