We took our son in February 2015 (trip report in signature) when he was not quite 17 months old.
I agree that you have to kind of go with what works for your child. Some kids are likely to nap in their stroller, for example. Others, not. And you may have to wait and see how it goes once you get there. We went back to our room (Desert Inn across the street, parlor suite) after lunch each day. Partly because it would get a bit warm. Some days he napped, some not. Either way, we hung out in the room for a while. He was a late walker and was still not super steady on his feet so he spent most of his in-park time in the stroller. The hotel was a great way for him to stretch his legs for a while and run around in the room. We brought plenty of toys with us...some favorites, some new.
We thought our son would hate characters. He freaked out when he saw a fake santa at
Walmart before our trip. So we didn't plan to meet any. Then we went over to Big Thunder Ranch and he saw Jessie from Toy Story and he ran right over to her. It was unexpected, but nice. We plan to take him next year (age 3) and once again, we won't plan to meet characters because you just never know.
We brought our video baby monitor since he slept in the other section of our suite. We ordered a pack n play from
amazon for $40 and had it shipped to our hotel (it was cheaper than renting a crib.) We bought diapers/wipes at Target but those can also be shipped from amazon or somewhere beforehand if you can't make it to the store. We also brought things to baby proof the hotel room...outlet covers and painters tape (to tape drawers closed.)
Our son wasn't good with using a plate at meals. So we had disposable placemats that we'd stick to the tables and he would eat his food right off of them. Easy and clean. We also brought disposable bibs and silverware. We had his sippy cup that we'd put milk in and meals and then just rinse and use for water at other times. We brought little snacks for him between meals...but we also got snacks in the park too (the kids Powerpack at some quick service places is great.) We didn't do any table service places because we knew our son wouldn't want to sit there that long.
We always brought an extra outfit in the parks, just in case.
Rides were so-so for him. He didn't really "get" it. He seemed to get a bit scared on some of the dark rides but he didn't freak out. He enjoyed Small World a lot and the brighter rides like Buzz Lightyear. We skipped some things he technically could have gone on like Pirates and Haunted Mansion because we didn't want to push our luck. I figured the screaming on the elevator of the Haunted Mansion would terrify him. And Pirates is such a long right that I didn't think he'd want to sit still for it.
Are you flying? I recommend bringing a car seat onto the plane. That's probably the best advice I was given before our trip.
This is long. I'll stop now.