I caught wind that Romney will next be in Iowa on Sept 27th and 28th. As far as I know now he will be at a event for Danny Carroll in Grinnell. He will also speak at the Principle Financial Group Luncheon. The event that I have the most firm details on is a breakfast fundraiser on Sept 28th in Cedar Rapids for Renee Schulte who is up for Chuck Larson's open Iowa Senate seat.
When I know more details I will post them.