The hotel is booked, your bags are packed, and the flight is leaving in a few hours. That's it, right? NO! That's not it. A seasoned traveller knows what to pack in a carry-on bag. Forget laptops and other work paraphernalia, diaper bags and slings, and anything containing crayons or dinky cars. We're prepping a grown woman's carry-on bag; the others are extras you, with the help of your partner — if he or she knows what's good for him/her — …