All business-class planes (and airlines) have been extensively tested as an idea. They tend to only work on the longest routes (1).

I too try to get business class on anything above maybe 6 hours and certainly on overnight flights, but I think you'd have to be pretty rich to not flinch at spending 2x or 4x your normal fare just to sit in a larger seat for a couple of hours on a domestic flight.

(1) http://www.singaporeair.com/en_UK/flying-with-us/business-li...