I have the feeling I'm the theoretical target for these movies - that is, I'm geek/nerd enough to know of the heroes' existence and to be interested in a super hero movie, but I don't really know much more about the universe than the "main characters", and I've never really read the comics.
GotG ...well, I went on your recommendations, and because it seemed goofy/fun. The original Iron Man I saw because I wanted a summer blockbuster, and for nothing more. In between, I caught a few on TV, ended up buying the DVD because I wanted to see them, and I saw....errr...I think one other in the cinema (ok, so maybe they're lucky I don't go to the cinema all that often for my type - most friends with similar taste simply go more often, and if I did, I'd have seen most of them in theaters instead of on airplanes or bargain bought DVDs). The premise of Ant Man is a hard sell, and where the trailers of GotG got me thinking "hmm, it might be fun after all", the Ant Man ones have me going "meh, why bother". This is not a good thing.