Emotional attachment to the beaches on Hilton Head as that's where we vacationed as a young child makes it a fave. Twice a year at the beach, once a year at WDW, plus lots of city visits was our family routine. My folks went away in the fall for an adults trip and one of our uncles would usually take us to Hilton Head then too (my folks would take my cousins so they could do the same). Really precious family memories, especially the trips the whole family would rent an entire row of beach houses and us cousins could live out Lord of the Flies - I mean get sent to Club Med type camps so our folks could play tennis and day drink, lol - those were amazing trips. The entire Hilton Head community is just so special. I should go there more often.
In terms of beautiful beaches, the Caymans, Puerta Vuerta, Jamaica, etc., etc. are beautiful. I could stare at those blue-green clear waters while eating whatever crawled out of the sea and washing it down with fruity drinks forever.