Rumlover,
There are many wonderful things in Kingston and Portland. For years Kingston has had a bad rap among tourism in Jamaica. I personally have never had a bad incident there over the course of dozens of visits . Your 35th anniversary to Jamaica only visiting Negril means that you have missed some wonderful places elsewhere.
Strawberry Hill is as you know a high end Chris Blackwell property nestled in the Blue Mountains above Kingston. You might find some Airbnb property offerings in the Blue Mountains that are somewhat more reasonable. The B-1 road from north end (Upper) Kingston goes up and over the Blue Mountains and past Strawberry Hill to the top a place called Hardware Gap and then down to the north coast at Buff Bay where it intersects with the A-4 road that takes you easterly towards Port Antonio and eventually all the way around the east end of the island and back to Kingston. Portland Parish is in my opinion the nicest on the island. Plenty to do in Kingston too. You might consider a trip flying in and out of Kingston which I find to be much easier to navigate than Sangster is. Rent a car and explore that end of JA!!
And I wasn't joking about Kingston! There is an amazing diversity in "Town", everything you could want is there. Well, except the incredible laid back vibe of Negril. Kingston is like NYC but Jamaica style!