Most domestic travel within the US is served by single-aisle narrow-body aircraft like the Boeing 737/757, MD-80/83, A319/320 which get you where you need to go but are otherwise boring.
On rare cases, there exists widebody aircraft serving domestic routes for the purposes of repositioning international flights or for large cross country loads. Getting on one of these domestic widebody aircraft can be an amazing experience especially if you are on a First or Business Class ticket because you get to experience an international quality seat for a domestic flight as opposed to a big recliner.
While difficult to find a full consolidated schedule of widebody aircraft on other airlines, AA actually publishes the domestic widebody schedule on its cargo website here.
The real gem for AA is when they fly 777’s on domestic routes. As an example of information that can pulled from this schedule, it appears AA will be flying the new 777-300ER on Wednesday May, 8th from JFK-DFW. In the current schedule, I also see the 777-200 listed everyday on two routes between MIA-LAX.
Finding these widebody aircraft on AA is near and dear to my heart because it was actually what got me hooked on points, miles and travel hacking. For the first full year of my frequent traveling life, I lived in Chicago and worked in Dallas during the week. American Airlines obviously dominates this route so I spent a good majority of my time flying MD-80’s down and back which I absolutely dread. One day a coworker let me know that AA actually flew a 777 on this route once per day and the aircraft was being sold as two class service for a three-class configured plane. With no status on American Airlines at all, we were able to pick Business Class seats on a 777 for this domestic route with an Economy ticket. It sure beat flying in coach on those MD-80s! This trick no longer exists but knowing which routes are served by a widebody aircraft can be a nice change of pace for domestic travel.