I think they should try and get the following off the ground:
1. Dr. Strange - heavy on the fantasy, dark magic, etc.
2. Ant-Man - I'm assuming this one is going to be more light-hearted?
3. A female led hero - It just makes sense. I'm not sure who though, either a Black Widow movie (meh) or someone else. Needs more thought.
Then you have sequels to the others.
Here's a crazy idea... since there's some reluctance to give Hulk a third whirl... what about a HULK/BLACK WIDOW team-up movie?