Did a week in Slovenia last July. I think its mainly the Triglav National park where Wild camping is not allowed but of course thats where everyone wants to be. It is stunning and the Slovenians are great.
One woman in the capital, Ljubljana came up to us and asked us if we needed any help or wanted to know anything about her city. Imagine that in London!
Whilst we liked Lake Bled and the surrounding countryside we didnt like Camping Bled. Most people who know us though know we dont like campsites but I thought it was grotty. Prices in Mid July where about €23 I think last year.
We did however like Camping Danica near Lake Bohinj and must prefered that lake. I think it was a bit cheaper as well and much nicer.
There are Aires and some are listed on www.campingcar-infos.com
One we stayed on about 10 miles out of Ljubljana was cracking and at a hotel. Sadly we were kept awake one night by a local dance which went on till about 2am. Another Aire we found in the mountains was passible but had a time limit of I think 36 hours max which seemed strange.
We wanted to see Brown Bears but we never did. Apparently they have so many they flog em to other countries. One turned up in the capital in the park one day (not when we were there).
Here is a link to last years Slovenia Blog
I would say its worth a visit for sure but like you, we would have stayed longer if it was more motorhome friendly and we werent forced onto campsites most places.
Last years Slovenia Blog