Went this last fall when my son was pretty much exactly 13 months.
We had a DVC room so we had a fridge and we did a grocery delivery so he could have whole milk, some of his usual snacks, and we had some hot dogs in the room in case of food freakouts.
We did quick breakfast in our room of cereal/granola bars and yogurt, etc. We toured the parks and then had a table service lunch. Then back to the room for his nap. He slept well in the pack and plays. Up around 3, snacks and stuff, we were usually back in the park at 4 and toured until about 7 and then he went back to bed.
We didn't try Wishes - he probably would have fallen asleep in his stroller, but my husband isn't a big fireworks guy anyway so I went with our older daughter and he took baby back to the room for bedtime.
His favorite things were: Small World, Tiki Room, any of the playgrounds (especially Boneyard at AK & the Mission Space exit at Epcot), & the Seas pavillion. Most of the time he sat still for shows, except the Disney Junior one (sitting on the floor, ugh!) and he got antsy at the end of Nemo and Philharmagic. He thought the Dumbo ride was ok - the playground was tough because there is a baby section he was a little big for (he is very large for his age) and then a big kid section he was much too young for.
He ate no problem at the restaurants - he is a good eater though - but he especially liked the meatloaf at Be Our Guest and he hated everything about Le Cellier except the bread. Buffets were a lifesaver because we didn't have to pay for him but he could get a plate of his own (did I mention he is a big boy - he often eats as much as his 4 yr old sister).
Let's see - travel messes with anyone's digestive system, so be prepared with an extra outfit always.
We planned to cold turkey quit the pacifier at 1 yr old but extended a month to have it during the trip - that was a HUGE plus - if he got antsy during shows I could soothe him a bit.
We tried several methods for carrying all his stuff and ended up with a backpack we just took with us everywhere. The amount of stroller parking and folding is too much to really store things all over. Backpack was a lot easier to handle.
We carried: a complete outfit change, diapers, wipes, empty sippy cups for water/milk, a couple snacks (goldfish, granola, etc), pacifiers and clips, ziplocks, disposable bibs and placemats, sunscreen, and a couple small toys.
The trips to AK and HS - he did sometimes fall asleep on the buses - it kinda messed up naptime so we were pretty happy on magic kingdom days when we could just keep him awake until we got back to our room (at Bay Lake Tower).
Oh - and he LOVED the characters! It was probably the best thing. Tons of great pictures.
