The film starts out based in sunny, smoggy L.A., but the death of Charlie's father takes him out to the Midwest pretty early in the movie… and then Ray's refusal to get on a plan turns the whole thing into a cross-country road trip.
So, Ray and Charlie truck on through a lot of different surroundings. No doubt because of Charlie's dire financial circumstances for most of the film, a lot of their travels involve dingy, roadside truck stops, diners, and motels. Actually, a decent portion of the film takes place in depressing little telephone booths where Charlie is trying to work out his business problems back in L.A.
However, once the boys get to Vegas and Ray's card counting talents win them some serious moolah, they end up in a luxury suite in a casino—a huge change from their digs for most of the film, and a pretty decent indicator that Charlie's financial luck is turning around.