Im also in the Fiji camp, been there a couple of times and there is absolutely no comparison to either diving in the Caribbean or Hawaii. Hawaii has the chance of seeing larger marine life but the corals and critters dont even come close to the South Pacific. I havent been to Turks and Caicos but have been to many other places in the Caribbean and I have a good idea of the type of coral and fish life that you would see there. Fiji has beautiful soft corals and tons of life. As others of said, it will be more expensive than the Caribbean but its a fairly easy over night flight from LAX. From IL you are going to have 3+ hours to the west coast and another 5-6 to Hawaii unless youre lucky enough to have a direct flight. For Fiji, you still have the 3+ hours to LAX but flight is a night flight leaving at 11 for 10 hours, you have a chance to sleep while still arriving in the early AM Fiji time.
If youre willing to travel longer distances, Indonesia is a great value. Sure airfare is more but the other parts of the trip can be very inexpensive. Recently, we were looking at doing a 10 day dive tour on Bali, 18 dives, lodging, guides, transportation, breakfast and lunches on dive days for under $1000 per person.