If what is meant by “stretch wrap” are the industrial rolls of plastic used to wrap/secure large items or large groups of smaller items together, it would be wise to remember that is also called “shrink wrap”. This stuff is strong and secure…and has potential to damage something as fragile as surfboards, most especially modern light glass jobs. Especially in warmer climates. Test it first! If you are talking the stuff you wrap leftovers in you are probably okay, but I would probably try it out a bit first anyway.
For the last decade or two I’ve preferred to travel real light, and real cheap whenever posible, so I haven’t dealt with a lot of the modern conveniences and expenses. I wouldn’t feel right if I didn’t mention the old standard - the sleeping bag. You get a lot of padding pretty cheap. It wouldn’t have the ease or performance of day bags and certainly wouldn’t look as cool, but it might solve the hard case internal jarring if you are destination traveling.
They didn’t charge me to bring my board home from Hawaii (counted as a bag even though it was longer than their max length which was 9’6" I think, mine is a 10’) but they did drop it causing spidercracks down one rail. That was with cardboard and bubble wrap all around Definatley going to use pipe insulation next time.
We just travelled back from Cali with 3 boards and standard boardbags which arrived perfectly even with glass on fins.
We wrapped rails with Pipe insulation as said before. We got special Nose and Tail protectors in Gary Lindens shop in Encinitas http://www.staycovered.com/Essentials/home1.html They are strong polyethyene. The guys with the fish bought the funboard pack as Keel fin Covers. They worked a treat. Bubble wrap and wetties sorted out the deck.
Definatley going to use pipe insulation next time.