Where can I find beautiful,scenic, wide long beaches with soft white sand and turquoise water (minimal rocks) and not go bored to death either if I want to leave the beach?

simply put...Anguilla. There are over 30 different beaches on the island. My favorite is Rendezvous Bay. It's about a two mile stretch of beach that is just breathtaking. The sand is super white and fine and the water a beautful blue and warm. There are tons of good restaurants and beach bars to explore as well. Never boring in Anguilla.

I disagree with Anguilla Girl.

While Anguilla does have 35 wonderful beaches and over 80 restaurants that's about all the island has to offer. There is precious little else to do on the island except relax on the beach and go out to eat. It may not fullfill eliware1's desire not to be bored to death when he/she wants to leave the beach.

That too, is the problem with most of the Bahamas Out-islands and the Turks & Caicos islands. They all offer great strands of sugar white sand beaches but they lack things to explore.

Aruba is one of the few coral/limestone based islands that has long stretches of white sand beaches and plenty of thing to do "off-beach". Grand Cayman would also be a better choice because of the abundance of off beach activities that are available.

7 Mile Beach in Grand Cayman or 7 Mile beach in Negril,,Jamaica...Cancun,Mexico on the caribbean side

Grand Cayman has the beaches you are looking for. They also have other activites such as horseback riding, Stingray City, various dinners, and there is a bubble enclosure that is fed with oxygen and protected on 2 sides by metal railings. The fish seem to be right there.

Eagle Beach in Aruba