One thing I just realized: in the episode where they say goodbye to the Japanese exchange student, they stand near him at the airport gate. Through the window you can see the hooded outline of a Boeing 747, or L-1011.
If Hiroshi (name of ex. student) were staying with them in a smaller town, he probably would have taken a connectio\ng flight from there to either Houston or DFW. With exception of Houston, Dallas, SA and Austin, no other Texas city airport has jets land of that size.
The other possibility, of course, would be that they rode with Hiro to DFW, Houston INternational, etc. from whatever outlying burg they were in. Yet that seems unlikely -- sending him off at the originating smaller airport would have been more practical. Plus, they don't drive yet. So that points to an area reasonably close, say an hour or two, from one of the big Texas airports. Would have to be either IAH or DFW, because those are the only ones with direct nonstops to Japan. They could have left from SA or Austin, and connected further west, like LAX, SFO, Portland or Seattle, but most domestic flights don't have planes of that size either. Verdict- they live in a small town, close to rural areas, but not too terribly far from either Houston or Dallas.
Makes sense?