We shipped down a pack of diapers (60 something count), wipes, antibacterial hand wipes, dried fruit, small cans of fruit, pretzels, and other snack stuff, as well as a 6 pack of juice bottles (plastic), sippy cups, glow sticks, small new toys, toiletries, etc so we didn't have to lug it through the airport with DS2 (luggage and carseat were enough). We ended up having a 51 lb box

! We shipped it UPS for about $31. DH dropped it off at Staples on Sunday (they don't ship out that day, but I couldn't carry the box) and it got to OKW on Thursday. I watched online so I knew it got there and who signed for it.
We also used the box to ship back souviniers, leftover diapers and toiletries, dirty laundry, etc. DH took it to the front desk at OKW, they weighed it there and he paid to have it sent home.
We will definitely do this next time, although we won't need the diapers

.