day trip to Julian Alps

I enjoyed my "Julian Alps Loop" drive a few years ago. I had no trouble navigating the hairpin turns - just had to take it easy. The most interesting thing to happen on the drive was encountering a flock of sheep coming down the road down the hill as I was driving up!

I'm not sure what else is on your agenda in Slovenia. If you have plenty of time to see everything else nearby, the tour might be worth it. Personally, I wouldn't put it high on my list unless I were doing it myself. There are lots of other things to see and do nearby I'd see instead. I had no traffic that September when I drove up the hill over the Vrsic Pass, but I understand it gets busier with tourists in July. Having someone drive me on a tour up the hill doesn't sound fun at all to me (I get motion sick in a car unless I'm driving, and those twists and turns would wipe me out!)

Sorry I can't help with information about these excursions, but I drove this route in May 2014. While it is twisty-turny, I didn't find it at all scary to drive in a manual-transmission rental car. It's not one of those roads with a steep cliff into the abyss just inches from your right tires. The twists are mostly surrounded by land on both sides. I've driven plenty of white-knuckle highways; this, to the best of my recollection, doesn't fall into that category. Your hesitation might not be warranted.

Thanks for your helpful replies. I've decided to rent a car and continue on to Piran.

Not sure from your reply if you will drive through Vrsič pass to see close up the Julian Alps, or go directly to Adriatic via easy highway route. In 2017, we drove the Vrsič pass route but only to village Trenta (we had terrific lunch at Gostilna Motoja) and then turned back to Bled. We made number of pit stop for sight seeing, and the round trip took six hours. As was mentioned previously there are some 50 turns in each direction, so be ready to use that clutch. For us, the drive was well worth it.
But I wanted to propose two alternate ways to see Julian Alps/Triglav National Park.

First, drive to Bohinjsko Jezero and take the tram to Vogel Ski center. That will give you nice views of the lake/valley and into the Julian Alps. After the tram ride, you can also take the ski lift up to the mid-peak, or choose to hike like we did (45 minutes at leisurely pace), for even better view toward Triglav, and can also have lunch at the mid-peak cafeteria.

Second, drive to Mojstrana and take local road 908 to Aljažev Dom. At end of that road, park the car and walk 1/3 mile to the mountaineering home (all flat), and from that location you will have a perfect view of Triglav that towers above you. We stoped there late in the afternoon, and had palačinke (crepes)....delicious.

Enjoy your trip.