I can’t find the Pixel Grid option like I would have in CS5. I just upgraded. Any ideas?
View > Show > Show Pixel Grid
Note: The pixel grid is only visible when zoomed in on any document. You won’t see it at 100% in most cases.
Another possibility, brought up by Lèse majesté, is OpenGL preferences. Do you have a video card which meets the minimum system requirements? If you view
Preferences > Performance, under Graphic Processor Settings, are those enabled?