Can anyone recommend a very good Slovenian owned travel agency that organizes trips there?
This company has good reviews and I have emailed with them about an upcoming tour but have not actually traveled with them yet: https://www.kopertours.eu/
No experience, but you might check out Dave’s excellent trip report for potential ideas.
https://community.ricksteves.com/travel-forum/trip-reports/25-days-in-slovenia
Here are a couple of leads:
PG Slovenia. Owned by RS-recommended guide and RS trip tour guide Tina Hiti. I did a couple of video tours (one of the Bled area and one along the coast of Slovenia and Croatia) with the agency during COVID-19 in an attempt to satiate my wanderlust and to support private guides during dry times. Those tours were excellent. And the company is recommended by the big man himself! https://pg-slovenia.com/
Elizabeta and her daughters do day trips but also arrange tours for large groups, too. I did several day hiking trips with her daughters, and they were excellent. https://www.topagencija.si/en/home