We really liked the breakfast at H&V. They could do with a couple of new characters, but as far as the food goes, the buffet was rather good. Your older kids might know JoJo and Goliath, and you get two characters from the Little Einsteins. They also do some singing and dancing to Playhouse Disney music. My kids (2.5 and 6) enjoyed it! They ate very well there too!
You can't beat being in the parks before they open! We did 6 character breakfast on our trip in December, with ADR's before the parks opened. I like them because we had to get up and get moving early. Otherwise, we'd sleep in and lose a large portion of the morning at the parks that way (as we did on our first trip in 2007). And as far as missing park time, if your ADR is pre rope drop, you really don't miss out on anything!
Enjoy the trip (and the deluxe plan - we loved it!)!!