I still say it would be cool to do this:
3 - Electro/Sandman
4 - Venom
5 - Carnage
6 - Sinister Six (revamped, with Lizard, Shocker, Rhino, Scorpion, Mysterio and someone else)
or
3 - Electro/Sandman
4 - Lizard/Scorpion
5 - Venom
6 - Carnage
Then like someone said, 6 can leave Venom for a spinoff, since they've obviously wanted one. I don't want a Venom spinoff, I love the character but I don't think he can be the hero to a movie and hold his own. I think he works great as a villain turned hero every now and then.