My son went for the first time at 10 months, then again at 1 year. Our biggest change from prior trips was taking a midday swim/nap/eat break. Before, we never wanted to leave a park to go back to the hotel, but this was the best decision each day. He LOVED the pool at AOA and we got to beat the crowds and heat and he woke up refreshed and stayed awake later to watch fireworks. He went on most rides that didn't have height restrictions...POTC, Haunted Mansion, Buzz, Kilimanjaro Safari, both boat rides at Epcot. We didn't spend that much time at HS, though.
I may have missed whether this applies to you, but I was still nursing for both trips (along with his eating solid food too), but only used the baby care centers on the first trip. I was disappointed that I didn't get to experience the one at AK, as I've heard it is the nicest. The one at HS has 2 private nursing rooms; the ones at MK and Epcot are large rooms. The one at MK was PACKED when I went...a lady was even sitting on the floor. So keep that in mind if you have any shyness when it comes to that. They have plenty of supplies at each BCC if you run out while in the park.
Take lots of photos!
