What's the weather like in Cancun in April? Historic and fun places to go wtih 4 kids and 2 adults?

I want to show my kids how beautiful Mexico is. They like swimming,movies,sight seeing, etc. They are 13, 11, 6 and 5. Also I would like to know if Riu Cancun, las Americas or Caribe would be better for them. And for me and my wife a relaxing swimable beach. Thanks