Wife and I are currently bringing back our mid century modern home's kitchen. We are about 1/2 into the project, so please excuse the pictures. The issue we are debating right now is the overall width of the peninsula. The peninsula is about 100 inches in length. The previous owners had installed lower cabinets as pictured, which weren't original to the house. We removed a floating cabinet which was above the peninsula, which we found to be just too enclosing (we want to entertain as well as eat meals on the peninsula, and we have 2 young children who we need to watch while cooking :)). We initially were going to remove the lower cabinets, and have a total countertop depth of 41 inches (29 inches covering lower cabinets, and 12 inch overhang) with a waterfall piece on the left side.

Here is another angle.

Now, we are debating about building a panel box and making the peninsula more deep. The cabinets are about 12 inches deep. If we kept the 12 inch overhang, and kept the lower cabinets, the overall counter depth would be 54 inches. Is this too deep? Take a look at a few other pictures of our kitchen. Would love some insight. We are doing a white cambria quartz counter.