We are just about to exchange but agreed our purchase just before first fix. We purchased a very high spec house but added heavy duty automation
The whole house has been wired for Cat6 to every plug, lights, blinds, front door, alarm, TV points and speakers throughout.
It was an initial chunky bill but when you see it in action, it's nothing short of fab. I can literally lean out from my new bed and switch the house off. And that thing you do when you go on holiday and wonder if everythings switched off/left a door open/whatever - login to the house and switch it off.
No cables anywhere - DS's xbox is in a cupboard with a TV on a wall - all wired behind the scenes. Ditto throughout the house - wireless simplicity.
Totally ridiculous but a godsend - I can blast music through the house to wake up my teen DS who I spend my life being a human alarm to via my phone - no more attempting to call him 27 times from 60 miles away!
More wiring stuff - I made sure the oven and hob were Pyro and Induction respectively, there was wiring under the units for hot water tap and waste disposal unit.
Outside power - ours is right to the back of the garden for when we recover from mortgage shock so we have it all in place to light the garden. We also pre-laid a hose to water the garden.
Garage lit and electric door, powered and multiple sockets.
Can you tell we became very good friends with our electrician??
Oh the other thing we didn't spec but our fab builder installed and are awesome, we have tilt and turn sash windows so you can clean the outsides from the inside.
Our banisters were already oak and glass but I upgraded the treads and risers to oak (and they weren't that horrific) so I could have beautiful stairs and not have to fully cover them - though that's personal preference.