Most front loading washer and dryers have the connections in the back and can be pulled out from the wall. So in this case the plumbing pipes/connections and dryer vent would be attached and then the units moved back into place.

Also remember, there is usually 4"-6" or so off of the back wall under the countertop/built in shelving that you don't see for room for the connections. The units aren't all the way up against the back wall.

For my laundry room/closet designs I ensure that one can access and manipulate the hot and cold water supply valves as well as the water supply hose connections at the washer without moving the washer. In areas with hard water, the filter inside the hot water supply hose clogs up over time, so needs to be periodically removed and cleaned.

As you suggest dryer venting is also a concern, so a way to verify and adjust the venting connection without moving the dryer is also important.

Access panels, and cut-outs in adjacent cabinets are two ways to accomplish this.

I am currently remodeling my laundry room and would like to use a black and white tile floor. What tile did you use?