Becareful with the Dakine Air Wagon, I loved mine, but I quickly paid more then the bag itself cost in oversize fees after only a couple trips!
It all depends on the airlines, some won't even question, but ones like Hawaiian will not even blink before they slap you with a $80 dollar fee (each way!)
Just took the NSI golf bag on a trip to Hawaii and never got any fees or hassle. Plus it fits 3 kites and a board easily. Padded just as nice as the Air Wagon, and a lot easier to tote around.