We've been taking our 4-yr-old for her birthday every year since she turned one, and we can't wait to do her next birthday soon! As a former Disney cast member, though, I can tell you that there's one thing to keep in mind for every family that visits the parks: "Wherever you go, there YOU are!" Many times, the families that come out miserable from these trips are the ones who imagine that the moment they pass through those gates, they will be the perfect family, having the perfect day with the perfect kids, surrounded by perfect strangers who magically know that this is all for making their perfect wishes come true. These families always come out screaming at each other. You know better, and you will enjoy a very happy trip because of it.
YOU know your child best, you know how much quiet time vs. excitement your daughter can usually handle. Some of our best birthday trips have been those where we kept coming back to the same quiet shady spot again and again (hint: from the central hub, cross the Liberty bridge and turn immediately left. There's a little courtyard behind the shops that's usually very peaceful!)
How patient is your daughter? Be sure to bring little baggies of cheerios or goldfish (not candy--the sugar roller coaster is NOT on your itinerary for this day!) and use them wisely. Grab those Winnie the Pooh fastpasses first thing, and plan not to be upset if your angel falls asleep just before you climb aboard. Dumbo's always a longer wait than it seems (no fastpasses), but slightly better at parade time; otherwise, Aladdin's Magic Carpets are practically the same ride, shorter wait. If you can handle doing meals at slightly off-times, too, it might help you get around. You'd be amazed at how many people are dead-set on having lunch at 12:00, dinner at 7:00. Let them. You'll have an easier time at the rides AND the restaurants! (Our favorite strategy: grab just enough of a bagel or something from home to get you started, go straight to Adventureland first thing in the morning, then have your Pooh brunch reservations for around 10:00--it'll tide you over till mid-afternoon!) Our favorite mid-afternoon lunch hideaway: Columbia Harbor House, 2nd floor (PERFECT calm, and they have some good healthy fast food, too). Of course, this trick is SO good that it often backfires--the place is so quiet, they decide to rope it off half the time!
Sorry to Grandma, but her first visit might not get to include some classics, such as Haunted Mansion, Snow White, or Pirates of the Caribbean. Then again, my daughter actually got more sensitive to spooky stuff when she was 4, so maybe this is your chance--again, you know the child best; and if you remember the rides well enough yourself, you might be good at distracting her at strategic moments!
Your daughter will get more exciting animal time with Small World and Jungle Cruise than she will at Animal Kingdom at this age. Also, don't overlook the Country Bears! That's a show that doesn't get nearly the crowds it deserves. Great breaktime, too! Another easy break--Tomorrowland Transit Authority. No line, ever, and you get to sit and enjoy the breeze while Princess watches the world go by. Same goes for the MK steam trains most of the time.
As for character time--aside from the Pooh brunch (and they do make it around to you, just be patient!)--if you can succeed with those Liberty-bridge naps, keep your pace relaxed, and make it till the end of the day, you'll often find that Mickey's Toontown Fair is pretty peaceful close to closing time. Mickey is in the Judge's Tent; and if you go through the shop next to Minnie's house, you'll usually find a good assortment of characters waiting inside (ask a cast member). The best situation is if you're lucky enough to choose a day when the park just happens to be open an extra hour or so past the parade/fireworks time. As soon as those "grand finales" are done, everyone battles each other to leave the park right away. In that one extra hour, those 50.000 people (and 8,000 strollers) MIGHT make it to the monorail station. In that same amount of time, you and your contented, well-rested child will have all of Toontown and Fantasyland to yourselves, give Mickey a good-night kiss on the nose, and enjoy a leisurely trip back to the car. Check the park schedules carefully, though--sometimes they'll close empty spots of the park a little early.
Lastly, remember that although the shops in the various lands shut their doors at closing time, the Main Street shops usually stay open till you have a chance to spend every last buck you have. No need to lug your loot around all day! And do keep those baby care centers in mind--even if you have to keep walking back across the park, the comfort and cleanliness of the changing area (or, if she's out of diapers--the kid-sized toilets!) will spare your sanity again and again. AND--if your daughter has any pockets that day, write out a little card with your name and cel phone # on it in case she somehow wanders off!
There! To sum it up--Go! Take her! And have a great time no matter what!!!