Looks like a good deal. I tried the dummy dates of Aug 14-21 with 2 adults and 3 kids (aged 3-9) using the kids stay, play free deal.
For a family suite at ASMusic, 7 day park hoppers and the quick serve dining plan it came to $3145.34.
Using the kids stay/play free you could get a room at a moderate resort - Port Orleans Riverside (sleeps 5 with a trundle bed) with 7 day park hopper and quick serve dining plan for $2832.26.
However, with 3 kids I would skip the park hopper. I too use touringplans.com to select which park I will go to on each day of my trip. I make up an itinerary for what park will go to then make all my dining reservations based upon that as well. I have been able to enjoy my trips with little ones without the added expense/time required for park hopping.