American Airlines flies what is possibly the single best product you can find on a domestic aircraft between LAX/SFO & JFK. Their A321T features fully lie flat first class and fantastic service both on board and on the ground (You get access to flagship lounges in New York and Los Angeles.) Normally first class awards on these routes can be tough to come by, however space seems to be wide open for next year.
It costs 32,500 AAdvantage miles for a Saver award in first class from LAX/SFO to JFK or vice-versa. Considering the service and product, this is a good deal. It can also be a great deal to tack this flight onto an international first class award ticket. For example last year I flew from Hong Kong to New York on Cathay Pacific and then New York to Los Angeles on the A321T. Since it was all one ticket, the total cost was 67,500 AAdvantage miles. It would have been the same if I had simply flown from Hong Kong to Los Angeles, so I was able to try out this product for free.
While availability is widespread, there seems to only be one seat available on most flights. Some days have multiple flights available and there are a few select dates with two or more seats per flight.