I saw this in August 2009, back when I didn't really like KOTH and was pretty much FG and Simpsons all the way. But it looked interesting, so I watched it, and found it pretty good. Long story short, the Hills and their neighbors have plans for thanksgiving, but get stuck at the airport. Nonetheless, they're stuck together, and manage to make the best of things by having pizza in the empty cafeteria.
Shortly afterwards, I looked up this episode. I saw November 2004 had an episode about the Hills going to Montana to see Peggy's mom, so I assumed that must be this. Turns out I was wrong. By that point, KOTH was definitely staling. Here's it's in its' prime. Whether at Thanksgiving or Christmas or whenever, feel free to treat yourself to watching this great ep.
Oh, as well as the hilarious YTP "Hank Hill's Airport Apocalypse", made by the fantastic EmperorLemon.