We bought our CX-9 (Tourning model) in August 2011. Currently it has 75k miles on it. City mileage is not great (low teens, I don't even really bother tracking it)...we have taken it on about 10 trips to Disney (from New Orleans) and routinely get 24-25mpg...that's driving at ~72mph, 3 people in the car (me, my wife and teenage daughter), enough luggage for 10 people for a month (meaning, they don't travel light), and nothing on the roof rack or towed.
Mechanically, aside from regular stuff like oil changes, tires, and wiper blades, the only issues so far have been:
* replace front brake pads at 70k (still had life left, but they were "getting there")
* replace both front power window motors (fairly easy DIY job, there is a GREAT video on youtube showing the steps)
* front passenger Takata air bag replacement (thanks Takata)
* replaced both front headlight bulbs (currently the right-front inner marker light is out...I'm not sure what you even call that because it's not a DRL)
For the last year, I've been getting intermittant check-engine light...I can't remember the code, but it has to do with fuel tank pressure. I replaced the cap with a genuine Mazda part, but it still comes and goes. If the thing would stay on for a month straight, I would bring it to Mazda to get it looked at, but it goes off on it's own, and even when it's on, doesn't seem to affect how it runs, mileage, etc.
We love it...it's easy to drive, I love the backup camera (which was optional on this year CX-9), handles great but doesn't beat you up, stops on a dime...it will be handed to our daughter when it comes time for her to drive.
One last thing...I want to preemptively change the fuel pump (because we all know, when they go, there is usually no warning)... I plan on joining some Mazda forums to ask around about the fp reliability in these, but if anyone here has any experience with the fp on these, please let me know. Thanks!