Hi Rachel,
My family visited Walt Disney World last year with my Dad and we all had a super time!
I think that it's a lovely idea to bring both sets of Grandparents along with you as a surprise and i'm sure that you would create many magical memories that your whole family would always remember.
We have been able to take advantage of the free dining promotion during a few of our most recent visits and I can't begin to tell you what a great offer it is and just how much money it can save during your stay.
If I am right in saying that you are a UK resident, I would recommend that you keep an eye on the
Walt Disney Travel Company website where you will find all of the current promotions. I do know that a free dining promotion has just ended but if one is to be offered for 2013, this is the place where you will find the details once announced.
To help you with your planning, I would recommend that you visit the
My Holiday Planner website where you can watch a number of videos including my top tips which are aimed specifically at helping UK Guests plan their trips to Walt Disney World.
You will also be able to order a copy of the Little Big Book of Magic guidebook which contains pull out maps and insider tips to help you get the most from your trip as well as a Walt Disney Travel Company brochure and some other planning tools.
Wishing you a fantastic holiday!