How Should I Spend 2 weeks as a solo traveler after a trip with friends?

Hi everyone. I am trying to plan a solo 2-week trip after Croatia this summer and looking for recommendations. For reference, I am a 25-year-old male.

Current plan:

• Portugal with family (June 4–12)
• Croatia with friends until June 22

After that I want to solo travel for ~2 weeks somewhere nearby without doing expensive long-haul flights to somewhere like Asia.

Right now I’m considering places like Montenegro, Slovenia, Albania, or just going to Greece or mayb even Istanbul.

I’ve already been to Prague, Vienna, and spent lots of time in Italy as well.

Looking for:

• good solo travel/social atmosphere
• nice scenery/beaches
• some nightlife but not only partying
• not too rushed logistically

Honestly open to everything. I'd appreciate any input!