I think Eddie Brock could be a great villain in a movie. Because, let's be honest, Venom was great for a one-time Villain, because he really only has one schtick: Revenge. It's hard to get a lot of mileage out of him, but he's essentially built to be a great film villain.
You could go a lot of ways with him. I think the SSM way could be a great version. Have him be the protective older brother figure for Pete, and throughout all the things that happen, he gets embittered and finally hates Peter.
However, one thing I would take from USM in this case: I would have the symbiote be something the Parkers/Brocks found during one of their research missions. They tested the suit, but realized it was a sentient being, and locked it away. Before they could bring it to a facility for higher testing, they died on the plane crash.
This way, when Pete finds this thing, he could think it's just some sort of advanced suit his parents were working on, before realizing it's actually a living entity.
That was one thing I always had a problem with in the cartoons/movie. Peter knew this thing was a living entity, yet he still wore it. It just seems foolish. At least in the comics he was unaware that it was alive. Using some of the Ultimate influence, we could still get something like this.