Their website has THE WORST scheduling experience you can imagine. You CANNOT see the available schedule unless you validate your Groupon first, then enter all your details (home address, phone numbers, DOB etc.) for all passengers.
We were trying to book a flight for Valentine Day, and I had to buy the Groupon first, only to find out their first available flight was the day AFTER we'd leave Vegas.
HAVE THE AVAILABLE SCHEDULE UPFRONT before you force people to purchase!