I have been twice, It`s only place I have ever been on holiday to a second time, I agree with Taffy on what he said.
We also did the two center thing, Guardalavaca for 10 day`s, up to Havana for the last 3, Amazing place, Amazing people.
We both time`s found deal`s with AI ( about £600 each ) Guardalavaca the First 10 days, then the Havana was B&B, There is not that much around Guardalavaca in the way of town / shop`s, So the AI is worth having, we went swimming with dolphins, Jeep Safari and skydiving onto the beach in front of the hotel, all throughly recommended.
Go there before the Americans can get in ! well they can , but they can not fly in from America, They have to go to Canada or there is some type of pass they can get, But too much grief for most tourists, The Canadians were great !!!
Have a good one
Tim
Edited to add
http://www.brisasguardalavaca.com/home.php is the hotel we stayed at, tell them it`s your aniverserary / whatever when you check in, We blagged a room upgrade both time`s, Both deals were through lastminute.com,