1) We had our son (4 years old at the time) earn money before we left, and we told him that he couldn't spend it until the last park day. So every time he saw something he "needed," I made a note in my phone of what it was, where it was and what it cost. The night before our last park day, we went through, figured out what he could afford and what he REALLY wanted, and bought it all then.
2) I also stocked up on cheap shirts from the
Disney Store and cheap pins on ebay. Since I knew what we'd do every day, I also brought cards, written in a "disney" font to leave with the gifts. I used the in-room safe as a mailbox and he woke up to a magical treat each day. Something like "Good morning Adam, please join my friends at me for breakfast this morning! Love Donald" on the day that we had an ADR for breakfast at Tusker House. It was also easier to get him out of bed each day!
3) rain ponchos are not created equal. We had high-quality heavy ones (purchased at another theme park in a rain storm) and we used them nearly every day. I was grateful for our heavy ones when I could see the cheap ones flying up in the wind all the time.
4) On our first trip, I brought two 11X14 photo mats for the characters to sign. They now hang in my son's room and they look fantastic. I can't say enough about how much of a pain in the butt they were to lug around, keep flat, keep dry, make sure nobody signed twice, get a good mix of signatures between the two, etc. For our second trip, they signed index cards. Since I don't do photo albums, but I do a photo book on Shutterfly, I just scanned the cards and put them with the pictures. They look great!
5) On my son's first trip, he hadn't flown before and I wanted to make sure he understood how long and boring the process is. So I did a sheet of paper with each step that we could cross off together (including pictures) - drive to airport, check in, security, sit and wait, board plane, take off, land, layover, etc.
6) Take advantage of the hotel's pool and other cool features. And spring for one night at a better hotel! On our last full day at Disney, we checked out of Coronado Springs and took a cab to Art of Animation, where we had a Nemo suite waiting. We didn't want to pay for a suite for a full week for the three of us, but it was very fun for our last full day and night! And since our flight left late the next day, we got almost two days to explore.