We chose to use PEX for the water supplies and the standard PVC for drains. PEX is great in new construction and gut rehabs because it allows you to run a dedicated pipe to each fixture instead of branching off as you go. This should keep water pressure similar for each fixture and allow the tankless water heater to work more efficiently (more on the tankless later). The brains of the PEX, you might call it, are located in the basement at the water supply and the water heater. Each line comes out of a manifold, a circuit breaker for water, if you will. This allows us to turn off the water to a fixture in the basement for easy repairs if necessary. The last two pictures below show off the manifold.
Last week, after an administrative snafu in which the electronic processing wasn't completed, we had a "rough" inspection scheduled for a Friday. However, when the inspector showed up, he thought he couldn't find the lock box and rejected the inspection outright. After some screaming and shouting on Twitter and via email, that was rectified and we were inspected the same day. The City really came through on that, because it allowed our drywall subcontractor to finish the ceilings and walls that weekend.