Universals character meals aren't as well done as Disney. I never done the Grinch, but we did the Simpsons, only Homer and Bart showed up. Didn't really spend too much time with my son. Another year it was Scooby Do and Shrek, seems they only have 2 characters come around. This was my experience with Universal. Don't think I will ever do it again.
Just go meet the Grinch in the parks - he's the cinema quality Grinch (the one you've seen in the Jim Carrey remake), the actors are great at improv, and you can spend some time talking and taking pictures.