I usually wear comfortable slip-on loafers on the plane, pack a pair of dress shoes, a pair of tennis shoes, and a pair of flip-flops for the pool or for wearing in the room. I guess I'm packing 3 pair, though the flip-flops don't take much space. I have wooden shoe trees for the dress shoes, plus shoe protector socks with cinch strings. The shoes go in slots in the closure flap of my suitcase. IE, I pack all my stuff in the main compartment, then close and zip the flap that contains 2 pair of shoes (dress & tennis - the flip-flops are stuffed against a side) with the soles to the outside.