They should have 3 with Toby as Spidey. Then 3 more with scarlet spider.
The symbiotes should NOT be in the spider-man movies, they should get their own series starting with Venom #1 where they have Brock get the symbiote.
Quick story idea:
Movie opens to a shot of a planet, flashes can be seen on its surface. Turns out it's the secret wars, screen does a quick fly-by of the action, and centers on a masked spider-man getting the symbiote. Narrator explains what has happened, skips ahead to when he returns to earth with the symbiote, does quick montague type deal. Like the intro to Lord of the Rings part 1, The fellowship of the Ring.
Venom 1 can center on brock and only have spider-man appear occasionaly, Toby might do it or they could have someone else. This would move spidey to a co-star part in this movie. End Venom 1 with Brock being arrested.
Start Venom 2 in jail, focus on Brock and Kassady. Follow the comics but twist it around a bit so spidey has less of a part in fighting Carnage. Make it more like Carnage and Venom comic where they are just fighting eachother, and add depth to Carnage by letting him open up to Brock about why hes so crazy. (Carnage is a deep character if you really get into him) Do not do Maximum Carnage storyline, just end 2 with Venom defeating Carnage and having him sent to Ravencroft.
Venom 3 could introduce some of Venom's enemies besides carnage and do like Spider-man 1, end it with him giving up his symbiote.
There ya go. Nice set of 9 movies for spidey fans.