DigiMark, I totally agree, they should do Alan Scott.
That way, it's okay if it's a bit hoaky, they can make it a period film, have it be 1930s/40s (keep it away from the war though, just make it a gangster era homefront movie). Think something like the Untouchables or Road to Perdition for setting, and then have Alan Scott blazing through it with the green flame. Not sure who they should have for villains, but a sweet fight with Solomon Grundy is a must. As Grundy is made of plant matter, Alan has trouble using his ring against him, so it would be an innovative battle, not just Alan bludgeoning the monster. Then maybe Icicle or Sky Pirate.
I think with the 30s setting and the mystical nature of the character, it could be a great movie. Not all of these superhero movies have to be set in the modern day, I think if the Fantastic Four movie had been set in the 1960s it would have been infinitely better, and it would work well with a character who does have a set origin period.