I would probably go along with a Spider Man The Animated(from the 90's) series story line. Where Norman Osborn is a relatively okay guy but under the Kingpin's thumb. I would also have the Hob Goblin as the villain of the first film and Green Goblin as the villain in the second. Ultimately the films would have a goblin in each film and be focused on Peter's personal relationships. For the first film I'd have Hob Goblin start out as an enemy for Kingpin and then have him switch sides. Then after kidnapping Harry he gets betrated and switches sides again. The film would end with Norman Osborn's "Death" and the second would start with a debut of the Green Goblin and have a big mystery as to who the Green Goblin is ultimately Harry finally learns his fahter is not dead was under Fisks thumb but his father dies and he goes even more off the deep end.
For a third movie I'd have a plot similar to third movie but I'd have more focus on both Peter and Harry and their respective journey's through the plot. I'd use the symbiote as a metaphor for drug abuse and have Peter using it to ignore his problems until he finally hit his rock bottom and realized he needed to get rid of it which would happen close to the end. After wards he'd have a final fight with a Harry and he'd end up losing his friend cut to the scene where Brock becomes Venom and cue the credits. The Fourth Film would be about Venom and would be a sort of karma is a bitch story line for Peter and the fifth and final film would be a Carnage storyline where Venom and Spiderman work together to fight Carnage.