It would have to be built using all the latest enviromentally friendly technology and sustainable materials where possible, with a grey water system for things like toilets etc. which don't require potable water, solar panels for electricity production, underfloor heating, quadrurple glazing, extra efficient cavity and roof insultation, etc Nice and inexpensive to run.
A jacuzzi, a sauna and a large walk in shower would be nice too.
I would make mine out of lead
I would have no sewer, i would just dump watse into a nearby lake
also i would have fireplaces that let out as much smoke as possible... )
I would have a deck on the roof with a 100-foot long waterslide ending in a huge pool D
but no houseboys D
If i ever build it i will invite all of you over for a swim in the pool [and then i will release the anglerfish... behead]
As long as I have a sunken livingroom, a big bathroom and a wrap around porch...I'd be a happy woman. Oh yeah, and one of those tubs that I can lie down and be comfy.