When my wife was building houses she walked the customer through the house before the roughs and marked all of the optional things on the floor with marking paint (phone, cable, paddle fans, floor outlets, extra receptacles for entertainment centers etc). She also marked door swings so you don't end up with the switches on the wrong side. It was good for the trades but it was great for the customer to be able to walk through the house and "try" the switch locations before everything was buried behind drywall.
She still tried to get another walk out of them before the rock went up.
