I did a trip to Slovenia Croatia and Bosnia last Autumn and a longer one a few years ago. We stayed on sites as wild camping is not permitted in either Slovenia or Croatia, and Bosnia is a bit wild and still has landmines in wild areas! Can get campsites in Croatia and Bosnia for around €15-20. In terms of development, Slovenia is first, then Croatia, then much further down the list Bosnia. The scenery is generally stunning in Slovenia and on the Adriatic coast in Croatia.
Bosnia is like stepping back into the 50's ... very poor, but lovely people. I toured there with my parents in a Dormobile in the late 1950's before they had metalled roads and although it has dragged itself into the 20th century it is still a peasant economy in country areas.
Slovenia - visit the Soca valley
Croatia - Visit Krk island, and it would be stupid not to see Dubrovnik to see it's historical significance ... but beware it is 200% touristy, full of crap gift shops and awful rip off touristy restaurants ... a mere shadow of what it was like in the 1950's when I was there! The Peljesac peninsula is very picturesque and Ston is Europe's answer to the great Wall of China and the wine on Peljesac is great! (It was the larder for Dubrovnik)
Bosnia - visit Jajce ... an ancient capital. When I was there in the 1950's the women were in national dress and the men on horseback with either swords or rifles slung over their shoulders ... no longer but it is a pleasant place. We also went to Mostar to see the bridge - now re-built - but a total tourist trap like Dubrovnik.
It's all subjective of course, but if you want something different, I would say give it a try?
Jeremy