Looking for recommendations for a place to teach someone to drive

My GF is learning to drive, so far I have taken her to a few decent sized parking lots (like the one in the Galleria's Best Buy after it closes) to get her used to the wheel and to turning in general.

Now I would like her to get to get more comfortable using the gas, so I'm hoping to find a bigger sized parking lot or find an area in town with low traffic, but I'm stumped for ideas, so I would really appreciate some ideas.

Thanks for the help.