My husband and I just booked a 5 square deal to Punta Cana. Does anybody know if they assign your hotel on a first-come first served basis? Do we need to get to the airport really early to get a good resort??

Your assignment to a particular hotel is made before you get to the airport.
It doesn't matter if you get there first or last. I am assuming you are refering to a square deal with Apple vacations.