Well, from a purely visual point of view, I would expect most male characters to have trousers and a shirt (whether sleeveless or not). Generally speaking, I would expect the females to have the same sort of dress code.
Characters like Black Widow, Marvel Girl and the like are what I would call sensible. They wear a decent covering. But apart from She Hulk and maybe Ms Marvel (who isn't sensibly dressed), what really powerful Marvel females are there? I guess Storm and Phoenix...but how many more? Male wise you have all sorts from Thing to Hulk, Iron Man to Juggernaut, Thor to Wolverine...it just seems to me that the females are there for icing rather than being the cake...and it is a real shame.
...and it is like Ajsalium was saying about Pepper, they just dressed her up in Armour even though she was a sidekick type character...
...maybe there should have been an Iron-Woman all along?