I had the opportunity to look for Rock Partridge during an essentially non-birding holiday week with my wife. We stayed at the Hotel Croatia in Cavtat, 19 km south of Dubrovnik, in Croatia, near the international airport. Cavtat is a pleasant, fairly quiet tourist village with a good restaurant (Galija Taverna) but I would not recommend the hotel - best to stay in one of the many B&B houses I think, pre-bookable through the tourist office. Dubrovnik is a beautiful walled city and there are several attractive smaller versions in the region, eg Ston to the north. The weather was warm - hot throughout, mostly sunny.
The only common birds of interest were Pallid and Alpine Swifts, abundant nesters in the old buildings. There are several wooded islands off-shore: Lokrum, a nature reserve, was the nearest and easiest to reach, by frequent ferry from Dubrovnik - a pleasant spot for bathing and walking but with surprisingly few birds, possibly because of the time of year. Both swifts were nesting in a cave just beyond the nudist beach, giving photo opportunities (if you are quick!) as they flew below eye-level.
The two areas of interest I did visit, on the 2+ days we hired a car, were the rocky plateau above Cavtat and the high mountains above Kotor. To reach the plateau, turn inland off the main Dubrovnik to airport road by the Cavtat turn, at Kerem Supermarket, signed Duba 14 km. Take the first left to Duba and drive up the mountain-side to the top. There are several roads on the plateau but the best I found was to take the first left, shortly after reaching the top, to Konoba Konavoshi Konim, a good restaurant at the small village of Velji Do. The road passes a coastal view-point, good for sunset-watching, and ends at Velji Do. It continues as a cart track, where Red-backed Shrike were common, and there are paths on either side, one of which has an info board showing a beautiful lizard and a Rock Partridge. Certainly, the habitat looks good for the latter but I failed to find any, not helped by my tape-recorder dying. I did see Short-toed Eagle, Hoopoe, Black-eared Wheatear, Blue Rock-thrush, Subalpine and Eastern Olivaceous Warblers, Sombre Tit, Rock Nuthatch, Red-backed and Woodchat Shrikes, Golden Oriole (abundant), Hawfinch and Cirl and Black-headed Buntings.
On a day trip across the border into what is now called Serbia and Montenegro, a country using the Euro as currency, we visited the lovely walled city of Kotor. Choughs, presumably Alpine, were wheeling high above the nearby mountain. The road to Cetinje climbed up into the mountains. We did not have time to go the whole way, unfortunately, but the habitat looked excellent for Rock Partridge, particularly after about 10 km where there is a good view over the rocks and scree. A Golden Eagle was the only notable bird I saw, in the afternoon.
The Neretva Delta, mentioned in Wheatley (2000), was a waste of time, being almost entirely converted to farmland. The only other sighting of note was what I took to be a Steppe Polecat Mustela eversmanni crossing the road in the hills north of Dubrovnik. Overall, I rated this region as a good one for a holiday with spouse, with plenty of sightseeing, walking and chilling-out opportunities, though better of course to go in May or June if you want to see birds.