Your panniers will receive much harsher treatment while on tour...leaning against trees... lying on the ground... exposed to the the sun and elements. They just ride around on conveyor belts at the airport and then are hand loaded into the plane out of the weather like any other suitcase. I zip tie my two rear bags together to make them one without an additional duffel bag. I carry on the others, put one overhead and one beneath the seat as others have suggested.