In general, I have a few 'Rules' I follow.
--Unless there is a reason to stay out at night with a young child (Fantasmic!, fireworks), plan on starting your day at a Park and try to be there for the opening - known as Rope Drop. Your ability to accomplish most 'must-do' attractions will come with little wait if you arrive at the Parks early. Utilize FP+.
--"The hotel swimming pool," was the most common reply when children answered the question of their favorite thing at Disney World. Leaving the Park before a meltdown is preferable to the alternative.
--Most children have about 4-hours to give inside a Park. For some children, this might even include travel time and meals. Expecting to spend morning, afternoon, and past dinner in the Parks is not an ideal vacation over 7-days, but maybe once or twice.
--Avoid crowds by eating early/late lunch. A typical dinner hour for children can sometimes be exhausting for them, and your best laid plans can cost $10/person in cancellation fees.
You do not need a touring plan to the degree that some of us have it down to the near minute.
But having an idea where you might start and which direction you might turn after one attraction or another will help tremendously in your leaving as if you did as much as you wanted AND made time for some enjoyment that may or may not be inside a Park.
Resources include:
--Direct questions on DisBoards
--Birnbaums for Kids
--EasyWDW (look at Cheat Sheet to understand each Park)
--TouringPlans after looking at books and other websites.