I agree, for what you are describing the Caribbean is the obvious answer, or Hawaii. Turks and Caicos is very nice, one of my favorite destinations.
From Seattle, it might be easier to get to Hawaii. On Maui, I would stay on Kaanapali Beach. There is a shuttle you can take to get there from the airport. Once there, there is the Kaanapali Resort shuttle to get you around within the resort area. It runs from around 9 AM to about 9 PM. It goes all over the entire K'pali Resort development-from Maui Kaanapali Villas (and Castaway's Cafe, good food) at the north end to the Hyatt at the south. It stops at the Royal Lahaina, up by the Fairways Shops (Cj's Deli, good spot), down to the Sheraton, Kaanapali Beach Hotel, Whaler's Village, then on to the Westin etc. It loops out to the golf course clubhouse and then does it all over again. To get to Lahaina you can take the bus, or if you stay at a Starwood property there is a free shuttle. You can lounge to your heart's content, or do a few activites if you desire such as whale-watching or go on a van tour of the Road to Hana. http://www.tourmaui.com/