If you get a room discount, then you MAY end up saving more at the GF than free dining. Free dining pays off more at the less expensive resorts, as you pay rack rate (something I've never done). For example, I just booked Pop with free dining, and it's only costing me $150 more total to add dining than the room only with a discount. That's for 7 nights for the 2 (or 3) of us (don't know if DS is going). For the GF, a 30% discount can potentially save more than a free dining plan. You have to see.
I loved the GF on my honeymoon, and really enjoyed it when we stayed with our DS (when he was 3, DD stayed with my folks nearby) but we were paying a military rate of way less than $200 a night. For a family, to me it's not as worth it, but I've been so many times. They used to do so many cool things, like no maid carts, just a basket of linens outside your door waiting till you left (they changed the sheets daily back 22 years ago, and replace all toiletries including a beautiful tin with a sewing kit - yup I had a dozen of those, kept taking them and they came by twice a day!). I could go on and on, but it's changed (it's still a great place, but I'd make sure you're comfortable with rack rate).
Dining plan is fun - I got it free a few years ago right before Christmas at the BWI, and at that time the promotion combined it with a room discount. I haven't seen that again! We didn't even use all our credits! I think we had a CS or two left. It's a lot of food!