This is definitely a two-edged sword... parking lots present lots of opportunity, but you have to create them by demolishing old buildings. Even in the last decade, the former CME building at Franklin/Washington was town down, and it remains a parking lot - not even a cheap taxpayer building.
I admire those cities that have refused to allow new parking lots to be created in their downtown areas - it makes building owners think twice before tearing down, because there's no viable way to make a vacant lot pay.