We decided, as I will often suggest, that the countertop be installed diagonally. The reason I prefer this is that most kitchen countertops are 25 inches deep from the front to the wall. This being the case it often looks better with 12″ tiles to set them on point either with or without a frame (being surrounded by straight tiles). If you do not do it this way you end up with a 1″ strip of tile along the back wall which looks very unprofessional in my opinion. By framing the center diagonal tiles it leave a nice, clean look and adds some “movement” to an installation rather than simply plain, straight tile.
This particular countertop is built with two layers of 5/8″ plywood and Fiberboard attached with screws over thinset mortar.
You can click on any of the images below for a full-size version.