My 20 month old has been to WDW twice, this will be his third trip. He's really pretty portable. We just ship a box to the resort one week ahead with diapers, wipes, snack crackers, juice boxes, ziplocks (all sizes), disposable sippys, etc.... Just write on the box "hold for guest "Mr. Suchandsuch arriving 11/24/08"
Oh, I would also pack some room air freshner (diapers!) and large kitchen garbage bags, there's never enough room for garbage in the hotel room, especially if you bring back food or have breakfast in the room.
You can purchase a package of Thomas' Bagels in the gift shop. These are great to keep on hand when they need a snack or toast them up in the food court for breakfast. The package costs $3.49 in the gift shop for 6 bagels or you can pay $2.50 per bagel in the food court. You can also purchase 1/2 gallons of milk in the gift shop.
If you dine at the buffets take a banana or some grapes for a snack for the baby for later (ziplocks). The waitstaff have always offered this to us, it was not my idea. They've even brought my boys two cups filled with cereal for us to take. They are very accommodating to babies.
Make sure to utilize the parks baby centers. Even just for a break and let your little one walk around or play in the playroom. AK and Epcot are our favorites as they're always empty. MK is the worst one and also the smelliest!!.
Should you little one be a good afternoon napper, I highly suggest making your lunch your big meal. You can dine with your little one fast asleep right at the table in their stroller. I've done the GF Afternoon tea several times with each of my boys on different occassions fast asleep beside me in their strollers. DH and I really enjoyed a nice lunch at the Brown Derby while our then 2 year old napped beside us.
Also try to get to the parks early in the mornings and leave midday. You'll avoid the heat and the crowds.
Regarding strollers, I've tried them all

The best one is an umbrella stroller. We love our Maclaren Quest. It's comfy for him with leg rests when he's reclined and it's light enough to carry on the buses. For added sun protection, I purchased a sun canopy and a battery operated fan. Make sure to pack your rain shield and a foldable tote bag to put all your stroller stuff (the items that wind up in your basket) in when you need to fold the stroller and board the bus.
http://www.amazon.com/Protect%2da%2dBub-Single-Canopy-Sunshade%2d-Navy/dp/B0007D9RJA
(this site shows a photo of my stroller with the sun canopy)
We skipped the crib option, it smelled! We just got bedrails from housekeeping and put them on all sides of the bed with some extra pillows in between. He slept with my older son and neither of them moved they were so beat from the parks.
Make sure to pack plenty of table time toys for restaurants and emergency items for meltdowns like bubbles or lollypops (Ring pops for my DS1). He gets antsy waiting in lines or for the shows when you need to arrive 45 mins before show time.
That's all I can think of right now. Anything else your specifically looking for??