Coming to Europe, I put my bike in a cardb oard bike box, packed it with clothes and gear up until the weight limit and flex with it. I made sure to put a couple of nylon straps around it just in case the handles ripped. Two flights later, I got the box delivered to me by a smiling trilingual Belgian woman, without a mark on it.
If you're just flying within conus, then check airlines, if the price is more than like $20-30 or so opver what shipping would be, then fly with it. The baggage apes were easy on my bike.