I have been to three of the four, some thoughts...
By "latter this year", timing is important for the islands. I feel August will be insane as Europeans, hopefully, are out of lockdown and that is the traditional vacation for many. September has always been a great time to go, October, some of the islands are starting to wind down, by November, things are noticeably slow to shut down, especially on the smaller islands, plus swimming and beach time is done.
Mykonos is a nice island, very tourism oriented, lots of shopping, nightlife, and beach clubs. Delos is just offshore, so you could easily do 3-4 nights, visit a few sights, watch some of the hedonism on the beach or join in (or avoid the party beaches for a quieter one). If the party scene is not your thing, you could do two nights and move on.
Santorini is also a tourist Mecca, including most cruise ships, Akrotiri and the cauldron are the main draws, some love it, some want to see it and move on. 2 nights for me would be plenty, others look at a week or more.
Crete is more like it's own country and not an island, it never really shuts down, though the beach resorts slow down. You could move to three different places and spend 4 nights each with no problem, doing Heraklion, or at least nearby for Knossos; Chania for just a wonderful town, and someplace else that peaks your interest. We did a beach town on the South coast, Matala, just to chill.
Rhodes, I have not been, an old friend from Sweden goes there regularly for beach time and loves it, lots of history, it is on my list. It is also the outlier of this group. The other islands are relatively easy ferries, but for Rhodes you will have to plan where it fits in the plan. Myself, I would consider flying from Heraklion, there are some direct flights. A ferry is also an option, long, and you will have to manage connections...but it might give the option to explore another island. None of the other islands you mention have direct connections to Rhodes, and a ferry will require multiple stops or connections (A connection can mean a few hours, or a few days until your connecting ferry), but as I mentioned, once you see where the ferry goes, you could maybe pick up an island on the way.