Munich to Croatia - tips for Croatia?

I really want to go to Croatia - no specific reason, it just seems beautiful. My partner and I decided, fuck it, let’s go to Croatia, and we’re looking at September into October timeline, probably about 10-12 days. Budget wise - we’re not rich but late 20’s, no kids, and both make good money so probably about 6-8k for travel + accommodations + spending……but we’re spenders (lol) so likely willing to go over budget.

I have a good friend who is German and I’ve never gone to Europe and not visited her, and with the September-October timeline, I figured we should probably go visit her in Germany and do Oktoberfest while we’re there. I’ve been to Germany before (to visit said friend) and she’s currently living in Munich so I’m not so concerned about that part but I wanted to seek advice for a few aspects -

- What part of Croatia would you recommend? + any recs for places to stay?

- How long do you feel is sufficient to explore said part of Croatia?

- Would you recommend flying from Munich to Croatia or another form of travel?

The first time I went to Germany I stayed with my friend + her parents, we went to Italy to visit another friend for like 5 days then flew back to Berlin (I had round trip ticket from USA to Berlin). This time, we’ll need to get a hotel as she does not have room to accommodate us. So, I’ve never experienced a trip where I need to manage having a hotel, leaving for a hotel elsewhere, then needing another hotel in the original place - is there a recommended way to book accommodations that account for leaving for a few days then coming back? (My thoughts are booking round trip to Munich then going to Croatia and back to Munich to fly home).

OR - is it better to book USA -> Munich -> Croatia -> USA ?

Sorry for the long post!! But overall, any advice about visiting Croatia + doing multiple European countries at once is VERY much appreciated