My youngest is an hour away by SouthWest Airlines. Like you I'm not comfortable with her flying alone even for that hour. But unlike you, I can make the round trip in under three and a half hours. I don't even bother with walking from the long term parking lot.

A couple of years ago the wife and I did the "planes, trains and automobiles" tour of Illinois/St. Louis.

We flew into springfield, rented a car and visited her dad. Turned the car in a few days later and took the train from Springfield to St. Louis. Flew home out of St. Louis. It was pretty cool and I would do it again without question. Gotta be wary of the train though - I hear in CA here it's not so happenin'