A good choice would actually be Roswell, New Mexico. Its airport has the longest civilian runway in America, due to being a former Air Force base. It has a lot of aircraft workers for its size, due to a lot of aircraft maintenance going on there as well. Plenty of space available right at the airport or just outside.
SC would have to come up with an unbelievable offer for Boeing to consider going there. It'd be like poking a hornet's nest with a stick..drive the IAM nuts..not worth the risk..
Roswell, NM is a fantastic place. America still grasps to life there.
Problem with 777X production would come from the fact that we are talking final assembly rather than true production here. Lots of parts made overseas, being shipped in, and, then combined for the final product. Makes a far inland place like Roswell not so good considering trucking wings and other sum-assemblies in from Houston or Galveston.
Long Beach, with its infrastructure, would seem an ideal place for such a project but the union seems dead set against gaining any further work. Pity. So Cal could use it.
Roswell, long runway? Didn’t realize those alien spacecraft needed long runways.