I agree with Lisa. Cancun is a great place to go, for what you are looking for. They have beautiful white sand beaches (here's a picture I took from my most recent trip):
http://www.megapixelworld.com/photog...=500&ppuser=20
I recommend the Le Meridien Hotel
It's sort of away from the noise, but in walking distance to a lot of things (should you need to leave the beach, LOL).
Let us know what you decide!