We had to preplan everything that was in the floor as well, kitchen cabinets, etc. We have two places where we have access through the floor for stuff - AC for electrical in the middle of the living room and an access for internet in my office - also in the middle of the floor. We built up special frames for the floor in those two areas and then I went to HD and bought two big orange cones that we put over the frames.

Then, when we floored those areas, I built covers with the flooring that could be punched out from below (there were 16x16 metal boxes in the ceiling of the basement) and when we were ready to move in, I switched out the access covers for the special ones.

Oh, I had another one where we did the same thing for where the TV goes. With all the interconnectivity and devices there, we put Gigabit Ethernet hard wired there. I didn't want to have to put it in the wall because of location, to the floor made sense.