Uhm, a central access shaft through which I would run all services which could also double as a laundry schute. Has the benefit of making laundry collection as well as maintenance of all plumbing/wiring easier.
Data cable (Ethernet/cat6) to all rooms.
UFH zoned and controllable for each room.
Airtight house insulated to within an inch of it's life. Passivhaus standards. Mechanical Ventilation with a heat exchange so that during winter your house is warm and doesn't stink. Also important for controlling damp in the house.
Smart lighting linked to a smart thermostat so that all lighting/heating/smoke alarms are automatic & voice controlled (look up nest & Phillips hue). Other cool smart house features like a google home. I am not personally convinced by the tech of smart locks for the moment because they seem unreliable but I would love something like that for keyless entry. Shuttereaze on plantation shutters on all external south & west facing windows that are automatically opening and closing in response to light detection/sunrise & sunset.
Ground Source Heat Pump for cheap heating (can potentially be around half the cost of Gas) - less important if you have a passivhaus.
Roof designed for optimum effectiveness solar panels because you can potentially reduce your energy bill to pretty close to zero with a good house battery and decent PV cells. If your property has any kind of stream flowing through it I'd investigate the possibility of domestic hydro. For it to be feasible it really requires a fairly steep fall and flow rate, but able to reduce your electricity costs to zero all year round (not just when the sun is shining!).
As loads of PPs have said, sockets to all have USB charging ports - Costco now sell them with 3100mA so you'll get a fast charge on even more power hungry items like iPads. They're like £7/piece as well, so utterly negligible cost increase.
Kitchen to have 2 double ovens to make roast dinners that little bit easier.
All flooring to have acoustic felt laid underneath the floorboards to dampen sound up and down, and all walls to have acoustic foam and acoustic plasterboard to dampen sounds through the walls.
Water accumulator with a good size tank; 500L+ with all your plumbing designed to withstand very high pressure (6-10 bar). Then you can live every day in your mega-shower with hotel type water pressure and flow.
Ensuite for master bed and a toilet/shower on every level.
Walk in wardrobe for master bed. Built in wardrobes where feasible.
Kickboard hoover so you can just quickly sweep the floors and have it disposed of rather than get the hoover out every day.
House-wide tannoy/PA system.
A method of cutting off the internet to all non-house-related use to motivate action when action is called for on the above tannoy (this would probably be more software related but if you had a google home there are apps that can do this; you could even create a voice command for it; "OK google, make them all come to dinner now" - bam, everyone gets kicked off the internet...)
Sufficiently large utility room to sort washing prior to use and to store washing prior to returning to where it lives. Make sure whoever plumbs in your washing machine also puts the waste pipe close enough to the dryer so you can have the dryer automatically send waste and you don't have to empty the damn drawer all the time.
Possibly a drying cupboard?
Larder/cold room - walk in, around 3 or 4 m2, with passive cooling
I haven't thought about this at all.....