When I think Maui, I think beaches, and Maui definitely does not have a shortage of beaches. There's lots of big sandy beaches like Ka'anapali and Big Beach as well as some more low key, smaller beaches. Some beaches are good for swimming, some are good for surfing, some are good for picinicing and so much more. So if you're going to Maui my advice to you is just get in a car and explore- you can't really go too far without finding a cool beach.
Oh and if you like the background music it's Brittni Paiva...
red sand beach
honokowai beach park