I <3 Dr. Seuss. I don't have a favorite work of his, although I like whatever is adapted to a movie so that I don't have to read it! So yeah, Horton Hears a Who is high on my list...
I've seen the animated version made some 30 years ago, not the modern one. The old cartoon is great! I can't stand Jim Carrey, and won't watch or own a movie starring him.
I read 3 Dr. Seuss books to my son tonight in honor of his birthday: Mr. Brown Says Moo, Can You?, Fox in Socks, and Green Eggs and Ham. My tongue is numb.