Well, aside from that I'm not sure who'll be smoking in or so close to your luggage that smoke odor will be a problem... even for adults, I'd tend to go with DisneyMomx7's suggestion. Not that anything like this WILL happen, but why not be prepared: Say one of your bags is chosen for a complete examination after you check it (different airports have different procedures) and somehow accidentally the one bag with all your underwear or all his shorts doesn't get put back in the suitcase - one of you is going to be doing a LOT of washing the one such item you wore on the plane.
If, on the other hand, you pack an entire outfit (or two) in each Ziploc bag and one disappears, at least you've still got MOST of your clothing.