Is POSTOJNA worth visiting from Zagreb and then onto Pliv Lakes

Well, it kind of depends on if you like caves...

But to make matters worse (or more interesting), you will also be driving more or
less right by Skocjan Caves, I suspect. If you're going to go out of your way to see
some caves, you might as well consider seeing some more caves.

They are quite different, so don't think it's just more of the same.

I will say that if you started from Zagreb (my assumption) and wanted to do both along
the way, you might not make it to Plitvice that day.

thanks for your response, I did notice that, but I wouldn't say that I need to see BOTH, maybe I should have asked if your goona see 1 cave which would it be?
We need to get too PL Lakes same day and not knowing the time limits on the border crossing.
Thanks

I’m not widely experienced with caves, but while Postojna is nice enough, it is not better than comparable “lighted” caves with litter baskets, stairs, and railings, in the USA. Not a slam, just trying to be helpful.

My point is that you spent a lot of money to get here, and rent a car.

Oh I'm sure, I don't know the cave system that well in US but im sure it's worth a visit and I will. I'm putting the CAVES IN SLOV because I'm literally right there in Zagreb, I have a rental car for 20 days and 2 hr drive is nothing so I've added it.
Thanks

One person's opinion on Skocjan vs Postojna....

• Postojna is much better lit, you can take pictures, and you are looking more
  at the formations than the dramaticness (so to speak) of the cave itself. There
  is also the castle, and a cafeteria/hotel in the cave complex area, so you can
  take care of tourist needs very well.

• Skocjan is a much higher and deeper cave complex. It is not that well lit
  and you are not allowed to take pictures until the very end (because, amongst
  other things, there are some very sheer drops long the way, and you're in
  pretty close to darkness, so you can imagine how many people would drop
  their phones into the abyss). There is also a river running through the cave
  canyon and that adds to the dramatic feel of the place.

There is a small cafeteria and restrooms at Skocjan but that's about it.

I am sure you will enjoy whichever one you choose.

If you want nature and are able to walk long distances and climb some stairs, go to Škocjan Caves. If you want a train and more of an entertainment bent, go to Postojna Cave.

I have posted this elsewhere in the forum, but there is an enormous cavern in Škocjan Caves that feels Lord of the Rings caliber. I wanted to grab a staff, slam it into the ground, and yell in my best Gandalf voice, "YOU SHALL NOT PASS!"

You won't have an issue with crossing the border between Slovenia and Croatia because they are both Schengen countries. We are also from LA and enjoyed Skocjan Caves. You should also see Predjama Castle while in the area. We liked the audio tour. You should spend the night near Plitvice so you can get there early the next morning. It's much nicer before the mobs arrive.

yes I've added the CASTLE to the itinerary, great news about the BORDER CROSSING. We are staying (2) nights at Plit Lakes then onto ZADER early AM.
THANK YOU ALL FOR YOUR HELP

Make sure you buy the vignette for driving on roads in Slovenia. You can purchase it online. We were stopped by the police and spent a nervous 10 minutes while they examined all our papers. They must have also checked online for the vignette because they finally let us go.