If it is possible to book a flight to Gateway, it's worth looking into, since it flies between regional airports that might be near you (e.g., best way to go see my brother in Iowa, since it has a direct flight to Cedar Rapids). However, the flights are still limited and you would not be able to get a flight in/out every day of the week.
Since Sky Harbor is the major airport, it has ground transportation available to Flagstaff
800-888-2749 / (520) 795-6771
And of course, I am willing to ferry folks if they are in town by Thursday 6/17 at noon. I do not have a big car, though, so hopefully, cactuswatcher can help out as well. I live within close driving distance to both Phx area airports, so that's not a problem.
Looking forward to seeing everyone there!