the perspective grid [ground plane, limited in size], and the cad-style view grid [I don’t belive it has a better name]
if perspective mode is turned on [hit numpad 5 in the 3d view to toggle it], or you are not in one of the major views [left/top/front/back/bottom/right], then the perspective grid will be shown
so to get your cad-style grid back, go to the top view [for example, you could go to the side or front…], then if it isn’t there hit numpad 5
Thanks, I wasn’t bright enough to realize that since my plane runs on top of the base grid, when I have wireframe mode OFF, my grid was being covered up.