I absolutely love hawaii, and would take it over the carribean any day of the week.
I've Been to maui, big island, Kauai and lanai
For a first time trip i would recommend maui- lots to do from beach, whale watching (during the season), haleakala volcano, road to hana experience, snorkeling, watersports, fishing, great amazing restaurants and the best seafood you'll ever have. I like staying in the Wailea area. You'll need a car in maui to get around - highly recommend the following restaurants: pacifico's, mamas fish house, milagros in paiea - awesome ono fish tacos and the best pina coladas on the island!
Lanai is amazing - two four season resorts - great restaurants and magnificent service.
Don't let l the negative nattering nabobs steer you away from hawaii - its a special place. To break the trip up take a flight to LA then overnight at a hotel and grab dinner in LA at a nice restaurant.