On the Warner Brother's side, Animaniacs, Tiny Toons, Pinky and the Brain are almost as good as the original Looney Tunes (which I also loved as a kid and still do).
I know Looney Tunes was originally geared towards adults (as short films before movies), but grown ups and kids alike love them. I've recently gone back to watch the classic Looney Tunes[1] and was surprised at how much satire was in them related to the 30s, 40s and 50s. It's the kind of stuff you would only really noticed if you studied the history of the era and are somewhat aware of the pop culture then. They were definently not meant for children, but the slapstick comedy and music draw in all audiences. Looney Tunes was my first real introduction to classical music. I would later go on to play Violin (probably somewhat influenced from Looney Tunes) for a number of years in school and still listen to classical music when I program quite often.
I don't know what happened to cartoons, but nothing seems to be interesting that's also geared towards children these days. Most just seem like some half-hearted attempt to educate children while attempting to be entertaining, instead of being entertaining and also subtly educating at the same time.
[1] http://en.wikipedia.org/wiki/Looney_Tunes_Golden_Collection
edit: elaboration