Cool stuff I have seen in homes dudes built:
Knew a guy who had a garage bathroom with a urinal in it. That was neat.
TV cubby hole thing on the deck, which sealed up to prevent water.
Loads of flood lights around outside of house that would turn on with alarm, and or when you catch kids tee peeing you.
Full baths for each planned kid, with tankless water heater (HS girls parent dream)
Laundry upstairs near where your clothes are actually kept