I would like to see Betty Ross in TA2. Even if its just a scene where she shows up to calm the Hulk down. It could be very poignant and bittersweet. I nominate Rooney Mara to play Betty.
I see her as a survivor, someone who's been through a lot because of Bruce/Hulk and her father. Based on TGWTDT, Ms. Mara can pull this off.