FYI -
Châteaubriand is a small roast extravagantly cut from the center of the beef tenderloin. In the 200 years since it was first prepared by the Vicomte de Châteaubriand's chef, Montmireil, we seem to have lost it's exact dimensions. Some people will tell you that it can be as little as 1-1/2 inches thick, which is essentially a tenderloin steak, and not châteaubriand. There is even disagreement in really old cookbooks, though, in which the meat ranges from three to five inches thick, and weighs 12 to 16 ounces. It should serve two to three.
IMO, if you find yourself in a place that serves this rather exquisite cut of beef than your visit there is likely occasion-driven. While ordering a ribeye wouldn't necessarilly spoil said occasion, save that dish for when you are closer to home.
I have had it a few times and only at one place about 75 minuts SE of WDW in Tampa called Bern's Steakhouse which as far as I am concerned (and most others as well) consider to be one of the finest steakhouses on the planet.
A little Bernaise on top, some Lyonnaise potatoes on the side and a glass of cab nearby and you will experience what I choose to call steak nirvana.