I was at LAS that night waiting for an AA redeye LAS-ORD that depended on inbound cabin crew. We were initially cancelled, but reinstated around midnight when our crew's ex-ORD flight miraculously slipped out and got airborne between thunderstorm cells. We left LAS a couple of hours late but luckier than many, and when we landed at O'Hare Saturday morning the gate scene was ultra-chaotic with flights that had been delayed all night finally loading up and getting out. Took us quite awhile to find an H/ K gate.