What is the most comfortable domestic airline to fly coach?

My husband and I are flying from Denver Colorado to Virginia and want to fly first class for the comfort factor. Unfortunatly we cannot afford it, so looks like we are gonna fly coach. What is the best airline that flys from DIA to choose?

I have flown domestic on American economy and its not comfortable( the 3-3 configuration)

I know the Airbus A340 is comfortable and Air Jamaica is one of the few airlines to serve champagne and a hot meal on flights (economy included)