We are a fmily of 5 too. We returned on 10/8. The dining plan was very easy to use. I just checked the receipt each time we used it to make sure the correct amount of counter service, table service or snack was deducted. We were planning on buying the plan, but got it for free. Here are just the table services we got:
LTT-lunch $115
Teppanyaki-dinner $168
Castle-dinner-$167
Crystal Palace-breakfast $88
Hoop Dee Doo- ALOT?not sure of cost, used 2 tbl service we had 2 more adults and 1 more child with us, for 4 adults and 4 kids it was $350!
One counter service at MGM for 5 of us, was $55! The rest of the time the boys shared alot, we just knew they would never all eat 1 cs per kid. Well worth it!