I lived in Zagreb 1979-1984 and visited Slovenia fairly often. I liked the Postojna caves, Bled, Ljubljana, Maribor, walking in the mountains and staying in mountain hostels. My friends used to laugh, because in the mountain hostels, my favourite meal was enolonce, specifically because each time it contained something different!
I also liked the fact that people in shops etc were always polite and efficient.
I translate out of Slovenian, but cannot use the language actively. I keep thinking about returning to Slovenia to do a course so that I can try to learn Slovenian properly!
My husband & I visited Slovenia in the early 1980s. I quite liked Ljubliana, but I really loved Lake Bled, with its little island & the church. We were rowed over on a gondola. The weather & scenery were amazing! Fantastic!