Looking to take my parents and siblings for a vacation end of May and looking for some recommendations. No kids, all adults. Looking for something relaxed, pristine waters (I am an amphibian), culture and history over crazy bar/night scene.

I won't be renting cars so cab will be main mode of transportation when going to explore the city or eat in restaurants.

If all else equals on the destinations, having a kick-... property (w/ Marriott or SPG or Hyatt) will be a tiebreaker. Got tons of points/PLT status between myself and my brother.

Any suggestions?