I'm very much in the same boat with only mileage being a concern. Obviously in this arena one cannot expect great mileage on a standard gas engine and diesels usually do not net gains worthy of the added price tag at this size vehicle.
Considering all the same you are including the MDX/RDX minus the GLK. In addition looking at the Volvo XC series and the VW SUV's.
The leaders right now are the Q5 with one of the subies not too far behind. I just need to get her to sit in and drive both to confirm. Q5 seems to be a great car for the $, subie obviously a less expensive car, pretty bullet proof but may not be appointed to the level she wants.
Ihsanshaik - X/Vasillalov - X/Nood1es - X/Countless more I can't recall - X