Dragonhelm
Knight of Solamnia
So I'm in the planning stages of a new campaign. I'm thinking I don't want it to be super serious/realistic. I'd rather it take inspiration from things like:
Thundar the Barbarian
Goltar and The Golden Lance
The D&D Cartoon
He Man
Thundercats
Can I play?

I'll second the idea of shifters for Thundercats. It's spot-on. I once based an early character of mine off of the idea of a Thundercat riding Battle Cat. In 4e, I'd make him a shifter.
Shardminds - Consider the Crystar comic books and action figures.
You might also look at the Visionaries. Also, maybe look back at Sectaurs.
Locales - Try to think of places with names like Snake Mountain, Castle Grayskull, the Crystal Castle (in Crystar). There might be some space travel, but you might consider doing the portal thing ala He-Man. Planets should have names like Eternia, Etheria, Thundera, Plundarr. Consider that sort of naming convention.
Magic Items - Consider magic items that have names, special powers, and a central purpose to the story. Think of things like the Sword of Omens, the Sword of Power, the Sword of Protection, the Havoc Staff, and so on.
Animal companions - Battle Cat and Panthor, baby! Over-the-top animal companions are always fun.
Hope that helps. That seriously sounds like a fun game.