I've been to WDW during Easter week a few times. I'll call it crowded...
Get to your park at rope drop.
And run to your favorite rides for the first 2 - 3 hours.
If you want a table service lunch or dinner, make reservations.
Get fastpasses as early as possible for the E ticket rides, use them, then get more fastpasses.
Don't park hop, you'll just waste time when you could be on a beloved ride.
Plan ahead! Arrive at rope drop, have your 3 FP+ made, have an idea of what attractions/rides you are going to see and in roughly what order, but be flexible. Some will tell you to stay at the park for the entire day, I like to take a break midday, especially in the heat of the summer, to go back to the resort for a swim/snack/shower and maybe a nap. Head back to the park in late afternoon/early evening as the heat will begin to subside and some people will leave the park for a dinner break. Keep hydrated!
One thing I'd add: take a 2-4 hour break every afternoon to escape the heat, grab a nap, and recharge your batteries. For me, touring when the crowds are at their peak (not to mention the temperature) is exponentially more stressful, and wears out my nerves and my body much more quickly than touring on a less crowded day. Give me a quick nap and a swim, and I feel like a whole new person -- ready to pound the pavement for a few more hours (during which the crowds and heat will only improve as time passes).
My family of 4 goes every July, we love the heat of summer so it doesn't bother us. We have 2 girls 13/12 and we just take our time and are patient. We plan our days (what park each day), dining and fast passes way before we even come down. We have the luxury of staying for 10 days so we don't have to cram it all in one day for each park. We usually say "we are going to this park today, what is the one thing you really want to do" Then we make sure those are done and anything else besides that and the fastpasses we already planned is just extra fun. We know its going to be hot and crowded and lots of tour groups in july, so as long as you know that going in, you are fine. We also tend to sleep in and close out the parks (due to heat), we used to wake up and do rope drop but waking the kids up early and rushing out usually irritated at least one kid and then ruined the day. Just my 2 cents. If your kids are little/toddler, getting up early is great, then just plan on coming back and napping for a few hours and go back. We did that for years when ours were small. Helped us parents refresh too
I have been during various hot and high crowd times of year and I HATE crowds and heat so I can help here!
I know it sounds so cliche and obvious but seriously: go into it with a lot of patience.
You will be hot and waiting. Just take deep breaths and realize that it will be like this, which it appears you already have.
You won't ride everything.
It will rain.
You will trip over many children and strollers as the pavement breathes 1000 degrees of heat onto your body while you choke on humidity.
If you go into it with realistic expectations, you will have a much better trip.
Take care of the obvious: Fastpasses, stay hydrated, plan down time, sleep well, sunscreen, and definitely book a few ADRs if you haven't. I find that sitting down in AC for a good meal helps us recharge and relax.
Something else that I find helps the psyche is to make a few simple, pretty easily attainable goals for easy day like "If we do nothing else, I want to (ride, do, eat at, see, shop at) today" and once a few of those goals are met, it gives us a sense of accomplishment and we are happier and more patient with whatever else happens that day.
You gave to book in advance 1st off to make sure you get FP and all. Also you have to go into the trip knowing there will be lines and decide what's worth waiting for and what's not. Bc of that I always recommend doing atleast a week during busy times, if not more.
Adding on to the wonderful advice that everyone else has said I would also do the following:
Bring your own or buy at least one misting fan (Don't forget that you can fill these up at any quick service restaurants, too).
Don't forget to bring extra sunblock in your park bag.
Bring a water bottle into the parks (that you can refill with water for free at any quick service).
These things won't help with the crowd but they should help with keeping you happier as you walk through the crowded HOT parks.
Personal experience has taught me that you should definitely get to MK by rope drop in the morning. You'll get onto so many rides- you can probably get onto everything in Fantasyland in under 2-3 hours without fastpasses. For parks like Epcot and HS I would recommend that one of those mornings at these parks could be your "sleep in" day where you don't necessarily have to be there for rope drop because you can easily fast pass the more popular/busier rides and walk on the others with little to no wait. For AK I would suggest fastpassing whatever is the most important to you in the am and then returning at night for the things you missed and possibly fastpassing more while you are on your break at your hotel. AK is (to me) the hottest park out of them all. I don't know why, I guess because it just seems so large, so taking a break midday would behoove you.
I made a mental note of all of our must-do's during my last trip the week after July 4th. The top of the must-do list was put on the FP list. We got those FPs for the evening. We go at rope drop and avoid the cattle call and herding. We tackled one side of the MK one day and the other side on the next visit. We did the same thing at Epcot. If we were able to slip something in on the other side without running back and forth, we did it. AK and DHS can be done fairly easily in 1 day. That covers 6 days of the trip. We were at the resort by 1PM and head back to the parks at dusk (~5:30PM). It was completely manageable plan. There will be no real walk-on rides after say 10:30AM.
I expected that Summer trip to be miserable. It actually turned out extremely enjoyable.
Yes this post I'm quoting is old, but I've got plenty to share. Any tips? Of course! Definitely get there VERY early as it may get more crowded as the day goes on!
Mind you this post is large, so take your time!
The bridges can be a mess during certain times, so try using the Walt Disney World Railroad while it's running (great time killer, shaded, scenic, relaxing, and a great place to rest your legs). Some attractions are shows that run over 10 minutes long (notably my favorite: Walt Disney's Carousel of Progress). When it gets closer to park close time, get in that last show for said attraction! You'll beat the messy crowds as you make your way to the exit (done it once with Carousel of Progress, and it works great!). If you're on Main Street and there's GIANT crowds exiting, the emporium is your friend! Take a shortcut through there, and you'll have GREAT luck at getting closer to that exit! Also try some less crowded attractions when it's super crowded, and maybe your favorite attraction will have less of a wait! The nights are less crowded, but some attractions will still have L O N G wait times. Try those attractions that are less crowded at this time that were crowded earlier (dumbo is a great example!). See an attraction with a huge crowd? Worry not with some attractions as their capacity per vehicle/cycle is HUGE! Ellen's energy adventure fills plenty of people in 1 cycle where as test track, not so much. See a crowd at Philharmagic? Worry not! The theater is large so the line becomes less intimidating when capacity comes into play! And that crowd at Carousel of Progress? There's enough people to fill a few rows to the point where there's no more seats in said row(s)! When traveling by monorail on the resort line, be sure to check for space to sit in a seat in some cars when you've stopped someplace to load people. You can also try walking across a car you're put in to find sitting room in another car, but that's not garunteed to work since the doors on the side opposite of where you got on close first, so there's that chance you'll be left waiting for another! Try to use shortcuts whenever possible as they could get you somewhere faster, if not, at the very least they'll help you avoid crowds. Be sure to get there early to get good spots for fireworks, parade, or projection show viewing (by early I mean VERY early!). The my Disney experience app -use it to your advantage to find wait times and make reservations for fastpass on the go (avoid the kiosks! Sometimes they will have lines just to use them!). Finally, make sure you check heights, and keep any children under 7 with someone at least 14! Some rides are only 2 per row so that's 1 14-year old (or older) for every person under 7! If you have the 6 year old go with the 12 year old instead of with mom or dad, it holds up the ride and also adds time lost in your day. Also be sure to stand side by side, keep up with the group ahead of you and fill in all that available space when waiting in line! You'll get there sooner and be able to get to that next ride quicker! That's about all I have to say!