Hello Harry!
Welcome back to the Disney Parks Moms Panel. It's so fun to help out a returning Guest. It sounds like you are planning a wonderful adventure for your family at Walt Disney World. I hope I am able to offer some insight to make your decisions on when to travel easier.
I have a seven year old boy as well and I have to say, he can wear out quickly in warm weather. Keeping that in mind, the average Florida temperature in July is 92 degrees, which is pretty steamy. Being from the south I love to visit in the Spring. Temperatures are wonderful and you can still enjoy the pools and water parks without it being too cold. I say an April vacation sounds practically perfect.
I can't say which will be cheaper as I don't know ahead of time what specials will be released during various times of the year. Keeping this in mind I advise you to keep an eye on the
Special Offers, Deals & Discounts page of the Walt Disney World website. All current specials and discounts will be listed there. As for crowds both July and April will have moderate to large crowds as Spring Break falls in April, and most people travel for summer vacations in June or July. I encourage you to plan ahead and utilize
Disney FastPass+ and
Extra Magic Hours in order to see and experience the most attractions and shows with the most minimal wait times.
I hope this has helped you out. Please let me know if I can answer any other questions for you. It's so fun to help out fellow Guests.
Dream as Dreamers Do,
Jen