The question that you ask is very tough to answer. I'll give it a shot. As a caveat, please note that I have spent far more time in the Carribean than Hawaii. I have only been to Oahu and Maui in Hawaii. I have been to numerous islands in the Carribean. (Mostly based upon geography, living on the East Coast. It is much easier to get to.)
I think that the answer depends upon where in the Carribean you are comparing Hawaii to. You mention SXM. I think the restaurants in St Martin (and over in Anguilla) are superior to what I experienced in Hawaii. Nightlife wise, St Maarten stacks up quite well. The nice thing about the Carribean, is if you leave the resort, you get to experience terrific culture. Whether it is Spanish (ie: Puerto Rico, Dominican Republic), French (St Martin, Guadelope) Dutch, British...plus the unique island cultures (not to mention food)...I feel like I have actually gone somewhere on vacation. In Hawaii...I feel like I am in America (because I am)...just with nicer beaches.
Having said all of this, would I go back to Hawaii again...and see and stay on the other islands? I sure would. However, the feel is very different from the Carribean.
Enjoy your vacation!