(Following Blackman's lead over here...)
Remember, just because a character exist, does not mean they are good outside of their medium.
Not about being recognizable isn't the big deal, the big deal is being able to build the character up on film. Iron man and Thor work because they can be brought to life on film and look badass in the here and now without many tweaks. Aquaman isn't Batman with a suit of iron. Aquaman isn't the God of Thunder. These are visuals that work on the big screen.
Actually, I'm going to counter with the idea that Aquaman CAN be similar to the God of Thunder -- that "Thor" shows one way to do an Aquaman film and make the character and his milieu stand out amongst superhero films.
The thing that Aquaman has going for him the most, IMO -- and the thing that can make him be taken the most seriously by an audience, also IMO -- is the "King of Atlantis" deal. You do for Atlantis what the "Thor" movie did for Asgard, you go all out in creating something visually wonderful and majestic.
You can keep echoes of Aquaman's orange-and-green suit if you want (primarily, I think, because it's recognizable to the general public, plus the fans would object if you didn't), while changing his overall look to the extent of giving him the beard that makes him look more "King Arthur" than "Ken doll generic superhero". I'd also argue that you skew him a bit OLDER than other DC heroes -- you don't put him in Hal's age-range, or Barry's, or even Bruce's. I'm not saying you make him "old", but you make him just a bit older and give him some experience (here I am comparing him with the "slightly older" RDJ Tony Stark, although obviously, tempermentally, Aquaman can't be anything like Iron Man).
The Aquaman being featured on "Young Justice" right now is a good example of what I'm talking about -- a little older, kingly, with a look set apart from the more "clean cut" heroes, yet not really shaggy or grim. There is no reason a live-action movie Atlantis can't work as well as live-action Asgard did.
Green Arrow is built around a guy who uses a bow and arrow and dresses like a Renaissance Fair fan.
I disagree overall with the objections raised so far to Green Arrow, for a couple of reasons.
First objection: Marvel is "getting there first" with including Hawkeye in The Avengers. Note: we haven't actually SEEN how Marvel is going to use Hawkeye in The Avengers, and given that he is only one of like 6 or more major characters, we have no idea how much he and his particular schtick are going to stand out. (This is not to say that I don't expect him to be good, or memorable. But the film isn't ABOUT him.)
Counter-argument: Marvel giving the general audience a good portrayal of a superhero character who "only" shoots arrows might, in fact, prime the audience to accept the Green Arrow concept even more.
Second objection: he "uses a bow and arrow and dresses like a Renaissance Fair fan". Okay. But on the flip side -- how well do Robin Hood adaptations generally do? (Leaving aside the most recent one, which did not come across visually/iconically as "Robin Hood" at all.) Answer: they do pretty well. Robin Hood is a relatively popular, extremely well-known action/adventure character, and has been for decades.
My conclusion: DC would actually be ahead of the game with the fact that they could market Green Arrow as "a Robin Hood movie set in the present", particularly if they really hit the sweet spot of making a "good old fashioned, fun swashbuckler" film married with a modern setting. Being able to play on the audience familiarity with and fondness for the Robin Hood mythos gives Green Arrow an advantage over Marvel's Hawkeye.
As to Wonder Woman. First, female lead. Second, Diana works best as Supes and Bats sidekick in the JL. I mean really look at the books. What part of that looks like it would work well on the big screen?
Also you then have to find someone that is as beautiful as Diana and is capable of not looking like a second rate Superman on screen. When you find a woman who is both that beautiful and capable from a physical end, you will have done something very impressive.
After watching the cavalcade of eye-gouging disappointment that was the run-up to the recent WW tv show concept getting justifiably and mercifully canned... I could not help but react to Jaime Alexander's Sif in "Thor" with, "well, there's your Wonder Woman right there -- get on that, DC".
Once again, "Thor" points out that even the general audience will accept a character with "mythological" underpinnings and a substantial background in a really out-there, fantasy-esque world. Wonder Woman, just like Aquaman, should, IMO, capitalize on what "Thor" showed audiences will go for -- give us a Woman Woman rooted in the DC version of the Greek mythos, and pull out all the stops. Make it tasteful and interesting, make her kick ass. Do all the things for her movie that "Thor" did right (pick a director with a passion for the material; get a good overall cast).
And don't underestimate the importance of the fact that even by herself, Wonder Woman has a huge amount of recognition with the general audience, and as a solo female superhero, she is really, really important to a LOT of people. Maybe not to you personally (generic you, I'm not singling anyone out here). But she is absolutely important. And here, I think DC would do well to capitalize on the fact that she is THE most famous female superhero in the world; far above any of the female heroes that Marvel has.