My husband & I had the breakfast buffet at the Grosvenor in October and I have to say that it was one of the worst breakfast buffets we've ever eaten at.
If I recall correctly, it was $14.95 per adult and we recieved 25% off with the Disney Club. It was offered 3 days a week (I'd call the hotel to find out which days).
Whe buffet was quite large, but the food was less than mediocre. It consisted of the standard buffet foods, Pancakes, bacon, sausage, eggs, pastries etc. The food was not hot by any means, and our server really didn't give a hoot about anything. They did charge us for juice & coffee.
The "Children's Buffet" was nothing more than a small silver cart with some pancakes, fruit and a few other things. The thing I found quite disgusting was that the children's buffet was in the corner, as you enter the dining room, and the kids were helping themselves with their fingers.
We had a terrible experience at the Grosvenor, it was so bad that we left 3 days early on a pre-paid ressie. They may have improved by now.