Most domestic economy flights, paid for in loyalty points/frequent flier miles go for 25,000 miles round-trip, almost no matter the route. A few carriers, such as American and USAir, allow a discount for holders of the right credit card.
On the other hand, British Airways, which doesn't have any U.S. domestic flights, sells seats on its partner flights with AA at rates based on a zone system, and can save for you that way. True, the West Coast is 25000 from New York, but Chicago and Miami are only 15,000...and you can buy a one-way for half that.
British Air's loyalty currency is called Avios. In the U.S., you can earn them with Chase's British Airways Visa. Two pluses for that: It usually carries a 50,000 Avios signup bonus, and earns 1.25 Avios per dollar. There's more information about this and other high-bonus cards in a Gumbo blog from last month.