Didn't you say you were leaving fairly recently? Or am I remembering wrong? (Not picking, just thought I remembered you posting that you were.)
Anyway, "retro's" a bit broad. Are you looking at trying to fit in with a certain style? Non "cape and tights" I assume? You can dig back for some inspiration:
The Shadow -
The Phantom -
There's always (1950s or so) the Phantom Stranger -
And the one I always think early Statesman stole the jacket from as a prank, the Rocketeer:
And staying in the air, the Blackhawks:
I said I was a bit busy but my schedule is starting to clear up, I'd never leave CoX, atleast...not for good anyway.
Blackhawk, Rocketeer, 1930s/1940s Statesman, The Shadow(Liked his movie btw), V (I know V technically isn't retro but he has the Retro feel), The Green Hornet, Dick Tracey, The Spirit and The Question (From Justice League). I guess we can throw in Zorro and the Lone Ranger since they're like...ultra-retro.
October 20th, I unlock trenchcoats so most of them will be doable.
Anything with a 1930s - 1950s feel to it really.
The backrground for my hero is that he started his career around the same time as Statesman but was frozen around mid to late 1940s and was recently thawed out when his cryochamber was discovered in the basement of an old abandoned science lab.
here's a couple to start you off. The first one i've made ages ago but never actually used, it's based on a kind of sandman/nightshade type design. The second is my retro hero 'British Hero' rad/dp. Hope they can give some inspiration 
Some of my retro heroes:
The Alt Alphabet ~ OPC: Other People's Characters ~ Terrific Screenshots of Cool ~ Superhero Fiction
You'll be seeing my new character running around Atlas Park soonish on Virtue.
The Azure Watcher.
I'll post an SS...soonish XD
Not quite sure if Comrade Hero is completely retro, but his original 2004 look certainly had that masked man of mystery vibe going on:
So, I got an idea for a retro themed hero, like Statesman at the beginning of the City of Heroes trailer when he stops the mafia from robbing a place. So, I was wondering if you guys can show me some of your retro hero costumes so I can get some ideas for my own costume.