The Kittyhawks and Forrestals from Iterali are 1/720. these kits are easy to put together, are about 15" long like Redbird said, and look even better with aftermarket railings and details.
For larger kits.
Revell did make the America and Kittyhawk. Monogram had the Kittyhawk and Kennedy in the same odd scale which I think was around 1/500 scale, I can't remember, I have the built model in my closet and it measures 22" x 7". These old Revell kits are large and easy to build as well. You can still get them on ebay.
Constellation was the same class (or style) as the America and Kittyhawk. All carriers have alterations that make them look unique. The old Revell kits will look all the same and will depeict the carriers as they looked in the early 1960s.
The Kennedy is a newer class carrier that was originally designed to be nuclear. She was a prototype to the Nimitz, but is a oil burner and is the only ship in her class.
Scott