You may want to call the DLH. When we stayed at the PP they were going to ship our christmas tree home for us. They may have some service at the hotel.
I know that Office Depot ships, there is one on Harbor north of the resort, near OrangeThorpe. But if you don't have a vehicle, you would have to take a taxi or the OC Transit bus #43.
The USPS "Holiday" Station is on Ball Road, due north of the DLH. In this Wikimapia view it's the largest building inside the rectangle marked "Former site of Cattleman's Wharf":
Good info to know! I'm thinking if I find a really special snow globe, or something else that's fragile, it might be better to ship it back to myself, rather then take my chances with it going in my checked luggage!!