I think you really need to have Hank Pym (and maybe Tony Stark) have a hand in creating Ultron or it's just, you know, Skynet. A movie could do some real interesting thing with how that guilt affects Hank, albeit with the hindsight of not making him a wife-beater in this continuity. Bonus points for not making him a wife-beater and then giving him a redemptive death. That's the most cliched direction I could see them going with this. That's the Brett Ratner direction.
Maybe you could have Hank working on the Ultron program for Tony along with Pym particles (which here also make possible a new kind of computer chip, like quantum computing) when Janet Van Dyne, a stockholder in Starktech, visits his lab. Subplotty goons show up, she uses Hank's technology to fight him, and Hank pretty much abandons Ultron to help Janet with her crime-fighting (and her pants, wink wink, nudge nudge, say no more). Ultron gets "jealous" and begins trying to kill her--hiring goons over the internet, commandeering robots, taking over automated factories--until you have this really interesting "love triangle" between a scientist, his girl, and his legacy, with Ultron demanding that Hank "complete" him by.
In fact (TL;DR), go the route of Ultron being based on Hank's brain scans, and he eventually wants to kill Hank to upload 100% of Hank's mind into his program. You could marry it with the Abusive Robot Boyfriend storyline from Iron Man, make Ultron into Jeeves 2.0. I'd watch that. Paul Bettany as an evil sexy robot... totally doable!