Film Should Have Had a World Setting
A problem with Ghostbusters 2 is that it's set in New York City like the first one. GB2 should have begun with the team being very successful as a result of their heroics from the first film (as opposed to being broke) and then being asked to confront a worldwide ghost infestation.
They could have had them fighting ghosts in Paris or Rome or Tokyo and thus expanding the scope of the first film.
Of course, Ramis and Aykroyd were forced to do a sequel so they probably wanted to keep it simple and make it a quick shoot so they stayed in NYC.