That sounds fun
I love when family and friends can join in.
My only tip to you, just take it easy. You'll want to show your friend's kids everything, but since everything is new give them time to absorb and remember what they do encounter. Running around and over planning tends to make for grumpy kids (particularly the young ones, but can make adults grumpy too
). Leave some magic under wraps for future visits.
You said that you're using the dining plan, but most folk find they can do far better by just paying out of pocket and using discounts (DVC, AP, Visa) I find the dining plan vs cash comparison tool at
http://www.distripplanner.com/ to be very helpful. The owner of that page tends to keep it updated with the current average prices for all locations. For some, the cost of the plan verses cash is too close and they like the feel of having credits to use on food. I can understand that.