Yeah Thor MIGHT be a bit of an odd one because he's not your straightforward "superhero". I know my mom remembers the old Thor TV show (I think from the 70s) (She had a thing for blondes!) but I don't know how many 'non-comics-fans' will really KNOW him. Iron Man was like that too, every Marvel/Comics fan knew him but the "audience at large" was kind of clueless on him, until the movie... NOW he's mega-badass.
What I sort of think Marvel needs to do more of is do short but sweet "intro to this character" type things on TV, like a made for TV special. Not a movie mind you, but a sort of documentary about. Introduce people to some of the lore behind the character. And then toward the end talk about the new movie. But make it more about the character. THEN make damn sure they sell the TPBs of some of the more "iconic" stories in every place that sells books. There's no excuse why a Marvel Masterworks type collection could NOT be sold at every store. Or even a non-movie tie in "Special" comic. The more people MIGHT know about the characters, the more they'll appreciate the movie.
And I always thought they should have guys in costume going to every theater or big event handing out small "ashcan" sized comics to everyone. They need to learn the finer points of guerilla marketing. Granted early buzz will sell tickets and if it's a GOOD movie, then the reviews and buzz from that alone will make it a success, but you still need to get people really interested and y'know what... maybe actually get people into the comics shops