You're better off simply contacting or visiting a granite supplier and receiving their input on what you need to meet your needs, and with the granite you are choosing.

I am having an u/c washer dryer put into my new kitchen. I was planning on having the counter be about 36" deep. I figured that with a standard 31.5" deep unit, + 4" in back for venting, 36" should be about right to have it flush.

garyboun - I actually accomplished what I wanted and I love it. My washer /dryer are underneath my cabinets with pocket doors that open and slide back in. It required wider cabinets but I love that they are hidden when not in use. Since I used pocket doors, I had to go wider so each appliance has double pocket doors. Because the dryer is not vented it's important to keep doors open when using. It's great during the winter because it heats the room up. Let me clean up the laundry room a bit and I'll show you pics. In order to accomplish the planning of my cabinets, I did find a washer/dryer in a showroom and took pictures so that I could plan where to put my plugs and drain hoses. I have those pics as well if you want them. The only thing that is a bit tricky is that the detergent fill-bin is located at the top, so you will need to be careful about your countertop overhang. My total depth of the cabinets with the w/d is 27" including countertop. Cabinet depth is 26 1/2" so very minimal overhang. There's definitely room in the back for it to go back further but I wanted to play it safe. At minimum I think the cabinet depth would need to be 25" with doors that overlay on top versus inset. As far as leaving door open to dry out, it's also necessary to wipe down the rubber flange of excess water so mold doesn't set in. But I typically leave door open when I'm done with laundry on both w/d for a bit before closing them up for the day. These are in my back door entry so it's really nice to shut them away. I'm really happy with the way it turned out. Let me know if you have any questions and I will see if I can upload pictures tomorrow.

Standard cabinet depth is 24"-26". Compact front-load washers & dryers will easily fit into this configuration. Alternately, cabinets can be 30" deep, which is considered custom. Many like that depth; some do not as things get lost in the back particularly with base cabinets. Standard size washers and dryers are not designed to integrate with kitchen cabinets because Americans tend to put them in a basement or into a laundry room. I would be very careful about keeping to kitchen aisle guidelines since it's easy to forget that cabinet and appliance doors need to open and in addition a person requires 24" of space as a minimum.