One thing I worry about is, how to get to a major surgical center without having to fly. If I ever need surgery (I'm at 4.2 now and almost 80), I'd want the best hospital I could get. That would require travel and I'm already hesitant to fly. This travel issue seems like a big one and nobody, so far as I know, has addressed it. Suggestions?

At 5.4cm you are thinking correctly, but you also need to think about timing. You are willing to travel to get the best care but that is probably something you need to settle very quickly, as @pamela78 says you don't want this to become an emergency as you won't be able to travel in that case. Planning for the best possible care is awesome but you should have a contingency in case of an unexpected event (read @moonboy's comment above), in an emergency you need to be minutes from an operating room.

Just in case mine was done at Memorial Hermann Texas Medical Center in Houston, by Dr Anthony Estrera (probably the best in Houston).

You are smart about being willing to travel. Again, high Volume centers provide the best chance of a great outcome. Also ask about retrograde perfusion to the brain. Different surgeons within a practice may do it while others will not. (Cognitive issues are among the most important to us.) The Cleveland Clinic in Cleveland Ohio and the Mayo Clinic in Rochester MN both have high volume good programs. Houston Methodist is another that publishes about innovative approaches. I am certain there are others on the East and West Coast.
We go to Mayo and are very happy. My aneurysm is at 5 but I don’t have vasculitis or other high risk “features.” It is stable and Mayo advised I could come back in 2 or 3 years but I want annual exams.
Good luck to you.