You can fly from NYC to Maui, round-trip for just $490 on Virgin. This is a pretty good price, but it works best if you’re also trying to do a quick visit of San Francisco because you’ll have a long layover there. It’s a great city after all. This sample flight from 4/28 to 5/5 has an overnight layover in San Francisco, from 8:45pm til 6:35pm the next day. There’s also a 8hr layover on the return flight.
There’s a few dates available, mostly in April and May. You can go to Google Flights and play around with the dates, until you find the cheapest price on dates that work for you.
Get the flight information and then go to a booking website such as CheapoAir,  Priceline or others to actually book the flight. Tickets cannot be purchased directly from ITA Software. You can also find the same price on the carriers own website.
There’s only a few seats left on each flight that has the lowest price so book sooner than later.
