The GOOD Stokke Bag
Very happy that Stokke came out with a functional stroller bag; the old travel bag got such abysmal reviews that we almost went with a different stroller, because we travel a lot. This bag is worth the high price-- very, very good quality, and hard to imagine another design that can accommodate and protect such an unwieldy bundle. One very minor word of warning: when packing the stroller with bassinet, remove the foam mattress and put it in rolled up or it could get pierced by the supports which fit inside the bassinet.
ProsAirlines will check it for free (because official, approved, etc).
Rolls up into relatively small bundle when no stroller is inside
Very durable fabrics, great workmanship
ConsBag is not magic, i.e. the stroller remains heavy and gigantic when packed, but once you've check it, that's the airline's headache not yours.