Our kids have been begging for a beach vacation, where should we go?

Finally, we have saved enough money (took a couple of years) to be able to take our family of four (5- and 10- year old girls) on a beach vacation like they've been begging for. If this is the only beach vacation/resort we get to go on, where do you suggest we go (and why)?

Beauty of nature and amazing weather, along with being family friendly are the most important. I'd love to go to the Virgin Islands (my dream), but that seems like maybe something my wife and I should do without the kids someday?

We're really new to all this!