Why not get a lincoln navigator? It gets 14-16 around town 18-19mpg on the highway. My mom owns a 2005, and its awesome. Drive when and you will fall in love. You can get a 2003-2005 anywhere from as cheap as 16-17k to 20-21k for a low mileage one. For 17-18k you can get one with 50-60K on it, not bad, imo.

Seriously drive one before you go buy a Infiniti, we drove it and multiple other ones, from Lexus to Cadillac. Navigator was by far the easiest full size suv to drive for my mom. She claims it drives just like her old town car.