I just drove from the DC area to Disney World in my AWD. I got varying mileage but nothing lower than 21. My highest was just over 23 mpg and that was with the AC on for most of the trip home. Speeds were between 60-80 mph depending on speed limit and traffic.
I usually get around 18 w/ normal mixed driving.
I just took a R/T Albuquerque to Denver last weekend. I averaged 80 MPH, and got about 19.8 MPG. I'm quite happy with this, as I swapped an Escalade for my CX-9. The Escalade would have been about 15 MPG on the same trip.
That's decent mileage for that trip. 2400 foot climb over Raton. Bet it was beautiful this time of year.
Do you have a 2007(3.5L) or 2008(3.7L)?