Once we explore the cavities inside Phobos, I'm sure it will be uplifted to preserve what is found.
So you watched Randall Carlson?
Valles Caldera was just the closest thing I could find to the Grand Old Canyon. As much as anything, I'm reminded of Guelb Er Richat, aka the Richat Structure.
Valles Marineris is probably the most hospitable location on Mars. I know Angry Astronaut named a crater where the temperatures reach 20 degrees (C. or F.?), the atmospheric pressure is highest, and water is adjacent.