There are a number of potential spinoff characters in the Spidey mythos. I suppose the obvious one is Venom (ugh), but there are also the Black Cat, various versions of Spider-Woman and Spider-Girl, Scarlet Spider, Madame Web, Silver Sable, Prowler, etc.
How about a movie centering on J. Jonah Jameson and the Daily Bugle
staff? Lou Grant
in the Marvel Universe, as the reporters deal with stories and crises involving superheroes and villains. You've got a huge cast to work with -- Jonah, Robbie Robertson, Ben Urich (assuming he's not part of the Daredevil
rights package), Betty Brant, Ned Leeds, Glory Grant, Norah Winters, and so on.