We have been to Hawaii (Oahu only) and the USVI/BVI. I have also been to Cuba, the Bahamas, and the Yucatan, but all were long ago and probably not valid in terms of my information or insights or even the reliability of my memory, so my comparison is based mostly on Oahu vs. the Virgin Islands.
Things to do: We did not come close to running out of things to see and do on Oahu. I could have visited Pearl many times over! Driving around the island and stopping at a food truck for lunch, quiet bays for swimming with or without snorkel masks, boat excursions, looking at the sea turtles resting on the beach, plenty of movie locations, luau options, a Polynesian cultural centre, the National Memorial Cemetery of the Pacific, Diamond Head, Dole Plantation, Haliewa, downtown Honolulu, and of course Waikiki. Accessibility varies, though many places were at least moderately accessible for my grandfather, who was 88 at the time.
For the Caribbean, we loved the Virgin Islands. Then again, we were on a sailboat the whole time, so I can't speak to accessibility at all! For us it was about sailing, snorkelling, beaches, and a bit of hiking on Virgin Gorda. So I am not much help there.
Edge: Far and away Hawaii (and that's just Oahu!)
Expense: I would say that both were expensive, but both were made cheaper by having our own kitchen. Hard to determine which was cheaper because our to-do and accommodations were the sailboat in the Virgin Islands. That ended up being cheaper for us for that reason. I would probably give the edge to the Caribbean
Cuisine: Varies wildly based on budget, tastes, etc. I will plead not enough information.
Safety: I wouldn't consider either destination unsafe, though of course for the Caribbean it depends on where you go and for any place your definition of safety is key to this determination. But I would probably give the slight edge to Hawaii here. Pickpockets are a thing at any destination, but there is little other crime that would affect you in either location.
There are so many great destinations in the Caribbean that I have not explored, and obviously without knowing more about the mobility of your parents, etc. I cannot make a determination. I can only share my experiences and hope that it helps you in making your plans.