Hi sav and birdman-
We will be in the Julian Alps all next week for some mountain air, scenery and wildlife, mostly concentrating on places above tree-line (and given that it is still May, below snow-line) within striking distance from our base in Bovec. Our itinerary includes Mt. Krn (SLO), Mt. Matajur (IT), the Altipiano di Montasio (IT), and the Mangrt Road (SLO). I'll do my best to write a trip report after we return.
If either of you want an off-the-beaten-path hiking option (for foreign travelers, at any rate), I would suggest the Kamnik-Savinja Alps NNE of Ljubljana. Much of this region is designated as an Important Bird Area. If you can do a hut-to-hut hike here (instead of day-hikes) then that's all the better, as getting to tree-line and above in this area usually requires a long, steep slog, and the hut-to-hut option makes it so you have to do this slog only once.
A suggested hut-to-hut itinerary:
Day 1 (Arrival): Drive through Kamnik and follow the stream called Kamniska Bistrica. Approximately 4 km before the end of the road is the Velika Planina cableway, which you might take for an easy lift to explore some pastureland at 1400 m to 1600 m. After returning to the valley, drive to the end of the road where there is accommodation in the Dom v Kamniski Bistrici (600 m).
Day 2 (Long Slog to Korosica): Leaving the vehicle at the Dom v Kamniski Bistrici, walk south along the valley road for maybe 1.5 km, where there is a trailhead on your left for the valley called Dolina Kamniske Bele. Follow the signs for the Kocbekov Dom na Korosici (or Korosica Koca - see picture), where there is accommodation and, interestingly, a high-altitude football pitch.
Day 3 (Korosica to Kamnisko Sedlo): Starting at 1808 m, follow the main trail west over Srebrno Sedlo (2115 m) and continue along to the Kamnisko Sedlo and accommodation in the Kamniska Koca (1864 m).
Day 4 - Option 1 (Kamnisko Sedlo to the starting point at Dom Kamniski Bistrici): This can be the last day of the tour, as there is a trail leading south from Kamniska Koca to the starting point at Dom v Kamniski Bistrici.
Day 4 - Option 2 (Kamnisko Sedlo to Kokrsko Sedlo): If you have the time and inclination (portions of this trail are quite difficult), follow the trail west for Turska Gora (2251 m) and Skuta. Before Skuta there is a trail that forks left to the Kokrsko Sedlo (1793 m), where there is accommodation in the Cojzova Koca na Kokrskem Sedlu.
Day 5 (Cojzova Koca to Dom Kamniski Bistrici): Follow the steep trail back down to the starting point at Dom Kamniski Bistrici.
There is great potential on the above tour for all of the high-altitude avian specialties, and you might see ibex and chamois and marmots as well.
As for your "brief spell" in Croatia, sav, I would suggest staying in Starigrad Paklenica, from where you can visit the Paklenica National Park and the nearby island of Pag, both noteworthy birding places.
Enjoy your travels, wherever you decide to go.
-Adam