I think a really cool story would be more like some of those Japanese tales from the 80s:

First part: a huge fleet of alien ships are detected approaching the earth. It is determined that the earth has 20 years to prepare for the fleet's arrival. We follow a young engineer involved in building a prototype Iron Man suit, and all the adventures as the team slowly perfects the suit.

Second part: The aliens arrive, and their intentions are hostile. We follow a young "pilot" who seems to have an uncanny ability to use the suit. The engineer from the first part befriends him, and acts as his mentor. Together, they become the most effective force in fighting the invaders.

(c) 1985 Qole Tojomokokodopopo productions.