I have been to Cuba 5 times now and always to Sol Cayo Guillermo. The first time i went was 2002. There were only 4 hotels on the island and Guillermo had the best beach I've ever seen, probably only matched by Pilar Beach at the other end of the island.
On my last visit, the best way to describe my reaction was 'shocked and disappointed'. Why? Who ever it was that decided to completely wreck the beach in front of the hotel should hang their head in shame. How to wreck a natural wonder!
And the high rise hotel next to Pilar Beach must have Ernest Hemingway turning in his grave.
Saying all this though, if you've never been to Cuba before, go. Some of the most amazing people I have ever met. It was like going back to meet old friends rather than a holiday and i had the privilege to stay with Carlos and his family in Ciego De Avila and to see some the real Cuba.