You can create a Grid alias. Basically set the grid the way you want it. Then right-click on the Grid icon (it's at the very top, right under the Open one), select New and give it a name. Now regardless of what you're doing, regardless of what the current grid is, you can right-click on the grid icon and select the one you created. Voila. You can do this both for the board and schematic views.
That was easy! Does the grid name and setting follow the project or does it set the grid the same way every time you open Eagle?