I went to the Grinch character breakfast last year, and it was by far the best character breakfast I've ever been too. The character interaction is outstanding. The Grinch does a great job of working the room, and he made several stops at my tables. The Whos also were very interactive. At one point, I went to take a picture of the Grinch, and he said, "Now you can put that on your facebook page."
I was by myself, and at one point the Grinch sat down with me, and asked the waitress to bring him salmon en croutte. He then gave me a hard time for eatting green eggs and ham. I lifted one of my glasses and said, "to the Grinch" and he took my other glass, and said, "To me." I had the server take a picture of me and the Grinch holding up our glasses, and used it as my Christmas card.
I also waited in a very long line to meet the Grinch once a few years back. They said it was a 20 minute line, but was really more like an hour. When I was about 100 people from the front, the Grinch came strolling through the line, and he stopped at me. He said, "You. How many in your party?" I said, "Just me." He said "Follow me." So I got to cut a good chunk of the line and had a private photo shoot with the Grinch and his dog (they had a real dog there).
It's definitely worth meeting the Grinch when you are there (the Jim Carey style one, not the one in the pictures above).