If you don't mind driving a bit, there's a daily A330 from PHL to LAX. You could book PHL-LAS and then take the redeye from LAS back to PHL. I haven't checked fares but if you fly outbound in F and return in Y it might come in under $900, but you can usually find a way to book a higher fare bucket. If you're seriously looking for lie-flats I think your options out of the DC area will be limited.