Bobert, where are you coming from? I would drive if there was any possible way, even to the point of renting a car. The gradual change in humidity would be better anyway. Keep them in your motel room at night of course.

Extra bags, last time I flew, can cost as much as $100 apiece. Find out what the 'surcharge' is gonna be before you get a nasty surprise at check-in.

One more option: ask if there are any flights (middle of the night, etc.) which tend to fly with low occupancy. If the plane is almost empty, then you can put your babies in the overhead bins while all your 'real' luggage gets checked.

I actually mailed a guitar to my new address one time, it crossed 5 states in perfect condition. Of course the case had the insignia of the Air Force fellow who gave me the case, so a bunch of patriotic handlers may have given it extra respect.