We went last year with DS, who was 2 at the time and still in diapers. We shipped a 50-some pound box at Staples (UPS?) for around $40. We knew we'd have our hands full with DS, his carseat and our luggage, so we needed to send stuff ahead so we didn't strain any muscles just getting there!
We sent 1/2 case of diapers, 2 packs of baby wipes, about 6 packs of antibacterial hand wipes, a 6 pack of plastic juice bottles, 1/2 full bottles of shampoo and conditioner, new little toys and books to keep DS occupied in line, disposable sippy cups, plastic silverware and bowls, umbrellas and ponchos, Chlorox wipes, bug repellant, dried fruit (foodsavered so it stayed fresh and bug-free), snacks, laundry and dish detergent, and some other random things we thought might look funny going through X-ray machines. We also sent two cases of bottled water from Staples.
We just threw out whatever leftover bug spray/shampoo/conditioner we had left at the end of the trip. We filled the box with souvies and leftover stuff from the trip down (diapers, wipes) as well as some dirty laundry to lighten our load. **We took a thick sharpie marker along to cross out the hotel address info and write on our home address info (marker was packed in the box, along with packing tape)**.DH took the box to the front desk at OKW and they got the shipping label printed out for it, DH paid, and the front desk took care of the box.
We sent the box to arrive 3 days early (so we had enough time to replace the items we sent and bring them along if they didn't arrive before we left) and were able to confirm with the front desk that it had arrived at OKW before we flew down. I had called the front desk at OKW to check on exactly how to word the address on the box. I also put the address on every side of the box, just in case of damage to one or more sides (as well as on a paper inside), but I only used the top 1/2 of each side for the hotel address, so I could use the bottom half for the return trip.
We also got a big sturdy garbage bag and placed all the items inside the bag, which was inside the box. That way if the box sat on the tarmac in the rain, our stuff would stay dry.