this is my experience with business class and first class...
i have friends who work for united. i can get companion flight coupons which will let you
stand by for first class or business class for planes with 3 classes
they are very cheap to get and i always get first class.... even that one time on 777 from Denver to Dulles, they ran out of business class...
and gave me a couch class boarding pass... then the lady says "hmmm, you're on stand by for business class, it's full, would you like to be bump up to first class?" before i could answer, the lady next to her says"yeah, as if he's going to turn down first class and go to couch"
funny, don't have to pay anything extra.