This has already gone out over Fare Alert so not sure how long this will last. As discussed on Flyertalk, there’s a $156+tax first class fare from Harrisburg, PA (just a few hours drive from DC) to St. Croix on USAirways.
Go to Travelocity (or the USAirways site), enter MDT and STX as your origin and destination, and select discounted first class for your fare type. (Or don’t specify fare type, it will still pull up this fare as it’s the cheapest fare in the market even for coach.)
Service is only on Saturdays — and only from Aug 12 to Sep 2 and starting again November 4 — so you either fly in and out same day (just under an hour in the airport!) or stay for a full week.
It’s an A fare which is a discounted first class fare and you are given the first class seat map to choose from. So yes, this is a first class fare.
Not all Saturdays will work. Since A fares are ‘discounted first’ they won’t be available on all flights, especially those that are already heavily booked.