You are so not insane. You will have a great time. Just come prepared. Know that you are not going for you anymore. Know that the kid dictates the day. Be prepared to find joy in the little things. See the World through his eyes.
Things to not forget to bring for the park each day:
Cover for the stroller, so that the little one can nap out of the direct sunlight.
A bath sized towel comes in handy as cover and as drying/sitting on ground apparatus.
Bring baby snacks that your little one likes.
Bring at least 2 changes of clothing and a pair of PJ's to the park with you, especially if you do not take a mid-day break.
Bring a sippy cup from home that your kid likes.
Bring at least one, "favorite" and you have multiples of it, small toy for company and comfort.
Bring lots of diapers, wipes, and a good zinc oxide based barrier diaper cream.
At Epcot, bring swim diapers, so that he can play in the pop-up jet water fountain.
Bring a warm baby blanket.
Ok, now with that out of the way, things to work on between now and then....
Get him used to wearing a hat and sunglasses if you can. I know it's completely hit or miss, but try.
Do what you can to lose the Binky! We were lucky in that our little one totally gave up the Binky and the Bottle at 12 months with no fuss. Not everyone is so lucky, but it sure is easier to not have to deal with either of those at the park.
Try to get the little one used to using a straw. It does help to not have to depend on the sippy cup all of the time.
Clothing-wise be prepared for a cool morning, a warm day, and a cool to chilly night.
We have found that at the end of a long day at the park that it pays to stop at a bathroom with the little one and do a quick diaper change, with a wipe down and clean up followed by a change into PJ's. It really helps get our little one to relax and give into sleep more easily. Plus, when you are finally back at your room, you just have to plop him down and then you can work on getting yourself more comfy without fidgiting with an overtired, cranky, still park clothed baby. It's not something that everyone does, but trust me, it works and when you are super tired too, it's really nice to have that out of the way, so that you can collapse on the bed yourself.
Bring gloves for you! Those stroller handles can get kind of cold early and late in the day. You may not need them, but it's best to be prepared rather than miserable.
I can tell you more stuff if you want. Like stuff about saving on pre-purchasing PhotoPass, just buy it, trust me, you will use it. Stuff about rides, Baby Care Stations, Companion Bathrooms are your friend, Baby Swap, and more.
Do I think you are insane? Heck no! Go, have fun, just realize from now on with a baby in tow, it's a whole new world. Personally, I like the little improvement.
