I'll give you the outline of my last plan in August last year. Stayed at Coronado Springs for 6 days (5 nights for DDP) with the standard DDP. The trip was for my 4 month pregnant wife and I and my 4 year old daughter and 2 year old son.
Planning becomes quite simple once you write down your expectations, it's all about execution and organization. I had 4 full days at the resort (2 others being travel days, even though my first day I arrived onsite at 9am). I will ignore the 1st day since all we did was play in the pool, visit with my grandparents who lived an hour away, and went to Disney Springs for a quick service meal at Wolfgangs.
Day 1:
Magic Kingdom (Rope dropped, got there at 8am)
Chef Mickey Lunch (Sit down meal)
Be Our Guest Dinner (Sit down meal we didn't use the previous day)
Plan out very early Fast Passes, then via the app you can sign up for additional FPs on the fly. Just jump from ride to ride with minimal waits. We made sure we did a sit down meal so get some rest mid-day with Chef Mickey.
Day 2:
Hollywood Studios
Picked out a place for Quick Service
Hollywood & Vine (Sit down meal)
We organized show times and did a bunch of the meet and greets. Kids loved the Star Wars marching up and down the blvd. We sat down at about 1-2 hours prior to the fireworks and relaxed in the evening. It was very nice.
Day 3:
Off Day for the Pool
T-Rex Restaurant Disney Springs (sit down meal)
Resort cafeteria (quick service meal)
I would HIGHLY suggest stacking "off days" or park "half days" in between full park days. When I list parks above, I'm talking open to close. With young kids it's going to be hard to keep up. Especially with the 3 year old and infant. Two days back to back to parks really wore us out. Me included.
Day 4
Magic Kingdom
Be Our Guest Lunch (quick service)
Crystal Palace (Sit Down Meal)
Second day back and finished up and repeated things we really loved.
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Key point here is to take advantage of the DDP and getting all the character meals we could and we had a freaking blast. Best trip I ever planned. If I had been there a 2 days longer, I would of added another half day, or if I wanted to splurge for a 5 day pass for tickets, I would do half days at the park like a water park or Animal Kingdom.
I always make sure to bring the kids to Disney Springs for shopping too.
Ultimately it's about what you like to do and UNDERSTAND your limitations. The more you plan the less you spend worrying about where to go and where to eat. If you have everything set up then you're going to have a great time without stress. Obviously there are tricks to this. Some advanced dining reservations are hard to get and there are services to help you snag them when cancellations come about.
Have fun.