Infernai said:
Watch Cowboy Bebop...no seriously, you should watch it.
Yes!
While you are at it, Samurai Champloo. Both are very interesting series, entertaining in their own right, but beyond that, they are serious attempts to create art out of the medium. Not in the same way as Evangelion, but they are very artistic in terms of their theme and overall arc.
If you liked Code Geass, then you'll like Death Note. It's got a lot of the same 'villain as protagonist' narrative, but it uses a more washed palette. Excellent use of composition.
This is an oldy but a goody. It's not a series, but damn if it isn't awesome in its own right: Otaku no Video. It's a HIGHLY hyperbolic and embellished tale of some nerds joining to form a geekmedia empire so one of them can become king of Otaku... the Otaking. It's also the story of the forming of Gainax, which is one of the most important companies in the field of animation in Japan. It's also a look into the mind of the creator of Evangelion before he got very sad and depressed.
Also... Neon Genesis Evangelion. It's very popular, it's being remade, but it's worth seeing. Don't see it in a marathon tho. It's... yeah.
If you must watch Akira, do not watch the dub dome by Streamline Pictures. I'm lenient when it comes to localizations, and not really on a side in the sub v. dub debate, but the most central plot point that explains all the wtfery was not included in the Streamline dub... yet was clear enough in the sub that watching the sub -made the movie make sense- when before it was just 'some japanese animated wtfery with awesome production values'. The animation in it IS top notch tho, Toei knows how to do it right.
And Gurren Lagaan. Yes. All I can say about it is... yes it's campy, yes it's cheesy, yes it's over the top. But once it goes over the top it goes 'LOOK A NEW TOP' and it then does what it can to go over that top. It takes 'Taking it to the next level' to the next level.
I also believe EVERYONE needs to watch Interstella 5555 at least once in their life. You remember those Daft Punk videos that were anime features? Well, in reality, that entire album was the entire soundtrack to the movie Interstella 5555, and the videos were just the parts of that movie those songs were playing in. No dialog, no sound other than the music, but it -works.- And for those oldschool fans: It's done by the people who did the original Macross.