Spiderman 3 wasnt that bad, it was the stories building up to the baddies that made it a bit boring. Maybe if someone were to hire the sinister 6 and all these baddies turned up without all the stories of how they got their powers, then it would be interesting. I agree with the clone saga stretching over two films comment, that would be cool.No. Spider-Man 3 suffered from having 3 villains so having six in one movie would be worse. Have the fourth as Lizard with maybe another then introduce the Clone Saga which would stretch over the next two films.
Black Cat if done well would be pretty cool, Alba won't be playing her if they choose to bring her in because of her involvement in FF.