Help with Slovenia -Croatia itinerary

Fast pace. Where are you going in Austria after Slovenia? That might guide your order of sights.

Kamnik would be a nice town for the latter part of day 8 (and for overnight). It's less than an hour from Velika Planina and has a nice old town.

Velika Planina is very cool, but I think all the summer herdsmen are gone at this point. It looks like the cable car and chair lift are still running, though, so you can go up and see the settlement and the nice views of the mountains.

The Solčava Panoramic Road is a nice activity in the Logarska dolina area. The website includes hikes of various difficulty (including easy) under the "Where to Go" link. https://www.solcavska-panoramska-cesta.si/en/

Personal preference: I would skip Krka on this trip (Krka is lovely; haven't been to the bear refuge to know what the draw is specifically for Croatia. It's so much driving - I travel at a fast pace but even I'm exhausted just reading your itinerary. Plitvice is definitely worth it, but I would try to see it in the morning or evening, which probably means staying AT Plitvice (there are sobe/B&Bs plus a few hotels right in the park). If you arrive mid-morning you'll be hiking the park with mobs of tour groups, and it can get really unpleasant, but if you go first thing in the morning you have the park somewhat to yourselves for the first hour or maybe two if you are lucky. If you stay at one of the park hotels, you can tumble out of bed and walk right into the park.

Perhaps you have some reason to want to stay in Opatija, and that's fine, but it really wasn't my kind of town, at least to want to sleep over in. It felt just kind of glitzy and expensive, though the waterfront area is pretty.

I agree with Dave that Kamnik is a lovely town.

It appears that Rastoke is only about a 40-minute drive from Plitvice Lakes National Park, so I think you can make that work. Be sure to get a really early start that day. You want to enter the park at opening time so you're ahead of nearly all the other day-trippers. That will make a huge difference in your experience.

You've given yourself mere hours in Ljubljana, which is one of Europe's most charming cities. I think you'll be sorry to leave. I'm sure Opatija is a pleasant-enough place (I've just passed through it once or twice on a bus), but Ljubljana is special.

This does seem like a lot of driving.

Plitvice lakes park. Start at the upper entrance the moment the park opens. You will be glad you did as you encounter the crowds coming at you a few hours later that started at the lower entrance.

Have you traveled with your 3 YO? Kids like to run around. Have you incorporated "run-around time" in this? Lot of time in the car. And, BTW, when in PL park you will need to keep a good handle on 3 YO. A lot of paths are plank walks over lakes, and a rambunctious 3 YO could end up in the drink.

I’d ABSOLUTELY slow down.

Your time estimates at places seem super optimistic to me. Example is Postojna Cave… I’m not sure how you’d park, walk to the ticket office, wait for your group tour, walk to the cave mouth, do the cave tour, climb back up the trail and walk to your car in that time.

Bled… do you want to take a boat to the island? That’s like 2.5 hours just doing that. You’re gonna do that, Vintar gorge and the Castle all in one day? It’s totally doable, but it seems like every day is like that…overstuffed.

I can’t remember the name of the cable car southwest of Bled, but that was pretty spectacular

I’d sleep at a hotel or sobe right near Plitvice. The crowd difference from open vs 1 hour later is pretty significant

Ljubljana is probably worth a bit more time but if you don’t care about the castle, you’re good. The best part for me is the party atmosphere /passeggiata along the river in the evening

Everybody goes at their own pace, but I just would feel so rushed if I did this itinerary. I’d feel like I was missing out on lots of “stop & smell the roses” opportunities. But I’m not you. You might think my pace is boring. Have a good trip.

For me as well fast pace. I would only do Slovenia and focus on this beauty. Where is the time to sit down and relax?