We've been seeing the best prices 4-5 months out, earlier if we can commit early. For frequent flyer tickets we've been booking the each flight as a one-way ticket as soon as the window opens 300 days out - those go fast. Our most expensive roundtrip ticket in recent years was $472 in March.

Spirit is a tough sell for us. It's got the tightest row spacing with up charges for reserved seats and carryon luggage. I'm booking two weeks in January and Spirit $47 less per ticket than AA & Delta, but $26 per carryon and $25 for a reserved seat eats the difference. The other challenge with Spirit is the single plane they have going to and from St. Thomas each day. If you miss that for any reason or its canceled, then your on the next available seat on a Spirit Air flight - no deals with other airlines.

Cheers, RickG