All of these resort brands are part of AMResorts, so these 50,000 points may come with a price - namely, being badgered to join their "Unlimited Vacation Club" (aka timeshare) program throughout your stay. Doesn't look like the promotion is contingent on you attending one of their presentations, but don't be surprised if you get the hard sell once you get on property.
That being said, they look like really nice resorts, and they are generally well-reviewed on the popular travel sites.