You can't rent by the month. Usually what people do is rent for a week. Then, renew the rental for another week over the phone. Two weeks is usually the max Hertz rents for. Each office can help you. Usually off airport Hertz is cheaper but airports have a better selection of cars.
Not sure but, the prices are really reasonable. It would also depend on your preference of vehicles. Give them a call. They have always been helpful to me on the phone.
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