No one should stay at an airport at CDG unless they have a morning flight from there or other compelling need for proximity. Staying at CDG and commuting to Le Bourget may make economic sense but at that point, the whole event might as well be in Omaha as to the overall experience.
I know it is very easy for me to say with no dog in this fight, but it is hard to believe that 400-500€ a night will only get a 2 star hotel.