There have been 1000 threads on this, but nonetheless, calvin and Hobbes was one of the biggest parts of my childhood. It was literally how I learned to read. I used to just look at the pictures, and then later on, started reading the words. I think that I am only missing Yukon Ho, Homicidal Psycho Jungle Cat, and the Tenth Anniversary from my collection.
I love the deeper meanings that you get from all of the strips when you re-read them when you are a lot older. There is no comic strip that will ever come close to the magical world that Bill Waterson created. It really makes you reflect on a lot of things in life.