I have a 2007 GMC Yukon. It was my christmas present from DH on our first Christmas as a married couple in 2006
It has this thing where it shuts down to a 4 cylinder on the highway so it's not as bad as you might think that big of an SUV would be. I think I average about 18 mpg.
DH has a 2007 Dodge Ram and it's a diesel, which is currently $4.85 a gallon here!
Fortunately for us DH has a car provided to him by his job and a gas card so he goes to work and back for free. And I work at home now so I use very little gas too.