[Dead Parrot]

I would include the drains and conduits for a sink and bathroom even if you don't plan on initially including one. Simple and cheap to include before the slab is poured. Expensive and PITA to add after the pour.

While running the electrical, include conduits for Cat 5/6 cable for Internet plus an dedicated 120V outlet for a computer/switch. Again, easy to add during construction, hard later. If you go with metal siding and roof, you may create a no cell phone space inside. Might plan on where to put security cameras in case those become needed at some point and run conduit to those places.

Might include several outside outlets for battery chargers and block heaters for vehicles stored outside.