I wish Doomsday was in it. I want to see Doomsday kill Superman in a movie. I'm serious...
Doomsday would definitely make that movie something to talk about, let alone WANT to see.
Spare no expense on the budget! Make a non stop action, large-scale disaster blockbuster!
I think Doomsday would have to come later in a franchise, since we need to establish a world that already knows and accepts Superman so the impact of his fight and his death will be stronger.
Also, if you haven't, try watching Superman: Doomsday. It's about an hour and 15 minutes, but so worth a watch.