Rates vary dramatically at DCA
This weekend, I have an Alamo full size for $15/day -- two weeks ago, the same car was going to be $40/day. My startegy when rates are high -- price via Orbitz and then go in through Priceline or Hotwire and bid 10-25% below. Almost always "win" and get a major renter.
Why rent when I'm local? I have a house on the Outer Banks and it is 300+ miles each way -- about 700 miles per weekend. Any way you look at it, much cheaper to put the miles on a rental car than mine plus the rental cars get better MPG than my upscale SUVs.