Raise your hand if you watched Arthur as a child! I absolutely love this show, and I know the names of all the characters, and I try to stay caught up on new episodes. It's been running for 14 seasons, since 1996. There are 334 episodes. I'm fairly sure I've seen all of them. Arthur deals with some pretty intense issues in a light, easy to understand way.
A lot of the episodes are about good lifestyle principles, like recycling. Some are about things like cancer.
My favorite characters are Bailey, Muffy's driver, and then Mr. Ratburn and Dr. Fugue, Arthur's teachers. However, there's also Paige Turner, the librarian. Since her name is a pun I can't help but enjoy her. The contrast between the adults and the kids on the show is great. There's also a large number of famous people who have made an appearance (Yo-Yo Ma, Fred Rogers, Andy Warhol, etc.)