rialtogrl "I’m a bit confused if you are starting and ending in Dubrovnik." My flights in and out are from Dubrovnik.
"I do not think going to Kotor for a day trip will be worth it." I agree, then I likely will have 9 nights to spend on 2 or 3 islands out of 14 total. For now, I plan to stay the first and last nights in Dubrovnik, 1 night (1.5 day) in Split/Trogir and 2 nights possibly somewhere in between Split and Dubrovnik. I prefer hiking with sea views more than inland hiking, It's not Switzerland, there is no snow in the mountains here and etc.
The question is how to divide time between Korcula, Hvar and Brac , which one has more amazing views? Also, may be one week car rent is an option when I finalize my route.

Among Korcula, Hvar and Brac, it would be impossible to pick which one has the best views--they are all comparable, really!
If I was going to use a car, I would do it in the Korcula area, because I think getting to the mainland would be easiest (just a short ferry hop near Korcula town), and the nearby mainland would be an area I would ;ike to explore with car (Ston, the Peljesac peninsula, and more)--but do check into Bosnia border crossings.

To AlexAlpha: Driving in Croatia is great. The highways are in terrific shape, just make sure your rental car has a toll vignette. The only problem is drop off. It's hard to do a loop in Croatia
We didn't spend time on any of the islands so I don't have advice there. But on the mainland I absolutely recommend that you not miss Plitvicka Lakes / Park, not too far from Split. It is crowded but there's lots of walking and the place is astonishing.

MichGuy you do not need a toll vignette in Croatia. Maybe you are thinking of Slovenia? They have cashiers at the toll booths in Croatia.

Thank you MichGuy, yorkshire and rialtogrl. I almost finalized my trip schedule. We are going to rent a car. Day 1-2 Dubrovnik, Day 3-4 Dubrovnik or Kotor, if Montenegro open.. Day 5 - Orebic' (for St. Stefan and vineries on the way). Days 6-7 Korc'ula. Days 8-10 -Hvar ( so I do not like a drive to mainland (2 ferries) and then take a ferry Drvenik -Socuraj, but I do not see better options). Day 11-Split (Trogir), days 12-14 Brela (Biokovo, Omis)', day 15 Dubrovnik ( Cavtat, near airport). May be I will replace Hvar with something else, like Mostar, but for now it is OK.

Rialtogrl is right, no vignette needed in Croatia, I was thinking of Slovenia. We used a credit card at the toll booths in Croatia and didn't have any problems.
AlexAlpha, you have a great, full itinerary set up. But if you're looking for a way to fill a day I can't say enough good things about Plitvicka National Park.