I would go with a white that has a slight gray cast, but definitely go white. You don't want to have the ceiling feel as though it is "coming down on you". With 8 foot ceilings you want to give the illusion of more volume, not less. Take a look at the paint fan to see what the lightest shade in the gray family that you are choosing from and see if their is a comparable version of white. (Wht brand and color of gray are you using?)

Here is an example of a project we just finished in Manhattan Beach with gray walls and white ceilings.

It will be a Kelly Moore grey. No blue in the hue. True grey. Like your suggestion. Thanks