Some more random hints I've thought of:
We took our own stroller. It was much nicer to have it around the resort, going to/from the parks, etc. The Princess has one of those big ones with the tray in front and to me, it's just a pain in the rear. We bought a Chicco umbrella stroller for $60--it's much nicer than the umbrella one we had when our kids were little. (That made it cheaper than renting one every day we were there, plus we had it all the time and can still use it when we take the Princess places.) It reclines, which really doesn't matter with her because she's too nosey to sleep when there is anything to watch; has a sunshade; and folds up easily. We got an extra mesh bag that hangs over the handles
($10 at Babies R Us) and it was great for holding OUR stuff. Since we got back, I've found a bag that hooks over the handles and has a cup holder and an insulated section. We'll use it next time along with the mesh bag. I've also discovered since we got back a "bottle bungee" which is a fabric thing that you can velcro around a sippy cup or bottle and then the other end velcroes around the stroller, car seat, etc. so the cup doesn't hit the ground when the kid lets go of it. Our stroller came with a tote bag that it fits in, so we put the stroller inside it to gatecheck at the airports. I got the bungee and insulated bag from travelingwithkids.com They have great stuff!
We also took a small tabletop fan (because I like to use one for sleeping) but when we turned it on, it would mask any outside noise--anytime she'd hear the whistle of the boat approaching the dock, she'd wake right up!
Because we go to Disney a lot, and this was our trip for the Princess, we didn't mind time to slow down and take it easy, which is good because I think it's very necessary with a little one. If you've been a commando tourist before, forget about it! The fun of seeing it all through her eyes made it worth it.
We were on the dining plan (free for those under 3) so we scheduled one ADR per day. Those worked well with the Princess, because we knew when we'd eat. We had 2 character meals, but she was scared of the characters. She loved looking at them from a distance but not close up! Once we realized that, we'd just wave them past us--the characters were great with that. They'd wave at her from a distance and act shy. I liked the TS places better with her, because we didn't have to stand in a long line to get food then search for a place to eat. When we did the CS meals, we'd try to go early or late and one of us got food while the other took the Princess and found a table. Finding each other is simple if the adults have cell phones.
As others have mentioned, take lots of clothes. Take lots of shoes. The Princess had 2 pairs of
Crocs, and her Mickey ones rubbed a sore place on the side of one foot, so she wore a pair of sandals we'd gotten at Old Navy just before we left (thank heavens!) for almost the whole trip. She always wore a hat when we were outside, and lots of sunscreen. Be careful on the boats if the hat doesn't have a chin strap--it might blow off! She loved sunglasses, but just as a toy--she wouldn't keep them on.
We took enough diapers for the whole trip plus some--used the extra suitcase room for the things we bought! We also took food from home that we knew she liked--cheese, her favorite crackers, etc. You can take baby food, bottles on a plane without coming under the "no liquids" rule. We took an unopened 1-serving size bottle of Gerber apple juice and 3 bottles of milk, plus an empty bottle. We kept it in the soft cooler with ice in a ziplock bag and threw away the ice at security, then got more ice after we went through security. You just show security the bottles--they didn't even question us--we'd just laid them in the bin.
I used a place called gardengrocer.com to order food in advance. We got individual fruit cups, a big bottle of apple juice, milk, yogurt, bananas, a case of water, wine for us, etc. They delivered it to our resort and it was waiting for us when we arrived. Bell services keeps the cold things cold for you until you pick it up.
We took a couple boxes of Gerber Graduate breakfast bars--she loves them for breakfast and snacks. We typically eat breakfast in our room, with or without the Princess. We eat breakfast bars, instant oatmeal, yogurt--much faster than going anywhere to eat, even the resort food court. The line there was always huge in the mornings when we walked by.
The Princess has fever seizures so we took Tylenol in our quart ziplock bag, along with a thermometer. We also had 2 small (8 oz.) bottles of Pedialyte, Little Noses, and Little Coughs in our packed luggage, but didn't need any of the medicine. Still, I'd rather be safe than sorry!
We took at least 1 gallon ziplock bag with us every day. You can stick wet clothes in it, extra food from a meal, etc.
We also took some of her favorite books, plus a few new ones. I found a little slate that she could scribble on, then erase and start over. We also took her favorite doll and a blow-up beach ball--a small one. She's obsessed with balls so we could blow it up after we got there and play with it in the room.
There were a few times we rented a stroller and they never had trouble napping in those either Of course, my kids nap anywhere when they reach their sleepy point - jus tlike their mom
We also did a lot of passing ds off from one adult to another. There's a lot of visual stimulation there so entertaining him wasn't a huge problem for us. When ds got a little older we put a safety harness on him so his hand didn't have to be up in the air all the time and he couldn't run under the queue rails or chains and get away from us (he was a runner! lol). Not for everyone I know but you'll see a lot of toddlers wearing them at WDW so you won't be alone. 
