Laura, do one of you work for a corporation that has a pre-arranged rental deal with any of the major rental car companies? If you work for a corporation, ask the travel dept if they have such a deal and can you use the code to make a reservation? Or they may make one for you. The best thing about car reservations is that they're very easily cancelled if you find a better deal.
If you're looking for very cheap and don't care about the car being dinged, look at Advantage Car Rental.
Also check with your auto insurer to see if they cover you for a rental car (rental insurance really jacks up the cost) so you could decline the rental car insurance. If you have an accident, you would pay your deductible out of pocket.
If you belong to any business associations they probably have a 10% off deal with a major rental company. Or AAA or AARP, all these associations have rental car member benefits.
Also renting on-line is usually cheaper than by phone or in person. They know they have you if you walk up to the desk and you don't have a reservation. You'll pay the highest rate.
When you rent, at the point of rental, they may ask you if you want to prepay your gas. If you're going to drive a lot and use up a full tank, this means you bring the car back empty of gas and they'll charge you to fill the tank at their rate. Be careful, depending on whether gas prices are going up or down, this can be a good or a bad deal. If you won't empty a tank of gas, do not take the deal, bring it back full of gas; you can buy gas 10 miles away at a cheaper station and it will still register full.
Many years experience renting cars. Good Luck!