Goodness, my dear, the upstairs maid takes care of such things.
monocle
We have a 3500 sqft house.
The basement has my workshop, my wife’s craft room, the laundry room, the guest bedroom, the guest bathroom, and the billiards room/minibar. The first three of those don’t need cleaning, the next two only need cleaning when we have an overnight house guest, which is fairly rare, and the last one doesn’t see much activity as my wife doesn’t drink and my kids aren’t tall enough to play pool.
The top floor contains the master bedroom, the master bathroom, and two master closets. Since we use one closet as storage, it never gets cleaned, and since we’re only in the bedroom to sleep and in that bathroom to bathe, they only need to be cleaned maybe monthly.
The middle floor is maybe 40% of the total square footage, and since we have kids that gets cleaned more regularly.
So we probably do as much cleaning in our 3500 sqft house as you do in your 1080 sqft house, because a large portion of the house is specialty rooms that don’t need much cleaning.
As far as “what do you get” that’s mostly covered already in “larger rooms, and more specialty rooms”.
We went from a 2400 sqft house to a 3500 sqft house. The kid’s bedrooms are slightly larger, and their closet space doubled. The master closet space went from one small closet to two large closets. Living room is large enough to add a piano instead of just fitting the couch and TV. Workshop space went from a corner of the garage to it’s own room. My wife’s crafts are in their own room instead of taking over the dining room table. We have a billiards room and minibar that just didn’t exist in the last house. The laundry room tripled in size and now has a wash basin and counter instead of just the washer/dryer. Back porch is maybe 4 times larger to fit the house, and has two levels. Total acreage the house sits on is 3/4 of an acre instead of 1/6 of an acre, so more space between neighbors and more garden space and more room for the kids to play.
Yes it costs more to heat, but it’s not much of a maintenance change, but it is more of a lifestyle upgrade since there’s more space.
You do get used to it. I forgot what living in a tiny apartment was like until my sister came over and went “you live in a freaking palace, I think my entire apartment would fit in your living room” and I went “we aren’t even close to the largest house in the neighborhood, and a couple of neighborhoods over the houses are twice the size” 
My house is 5,000 sq ft (well, I think 4,975 formally). Previous house was 6000. I do feel a little cramped in this one, mostly because the previous one had a pantry that was much bigger, and half the basement was storage room, which was nice - but otherwise it’s ok. 5 br - ours, two for the kids, one that is wife’s office and one guest. It is nice and cozy.
I don’t know what I’d do with 10,000 sq ft house. But 5K is just about right.
Layout really matters in houses that size. A couple of moves back I owned a house that was 4,500+ sqft. with 4 bedrooms and 3 baths. Due to the layout the downstairs guest bedroom had a weird room between it and the media room that could have worked as a living room for the guest room that already had a sitting area as part of it as it was we had my brother-in-law living down there and the only thing that room got used for was storage and as a giant hallway a total waste of 400 sqft. Functionally that house was 3,000 sqft due to some weird layout issues but a lot of it was common space that needed to be kept clean since it was where guests would be it caused my wife and me to hate large houses
All that said if I got to design a custom house I’d be looking about 7,000 sqft once I got all of my preferred specialty rooms in place and sized for what I’d prefer.
I have clients with a 9,000 sq ft house with only two bedrooms. They don’t have kids, so they have a master suite, which is huge, and a “guest suite” which is also quite large (with a small kitchen). The have a large home gym, two home offices, a giant great room, a wine cellar, and a bunch of bathrooms.
I wonder how easily such a house would sell. I would expect difficulties.
Well, it’s always hard to sell a $10M house, but I can see a couple with grown children wanting a breathtaking home for entertaining and such. Also, it’s ADA compliant.
Larger homes ( 4,000 square feet or more ) often have a great room inside of them that has 400+ square feet in it for entertainment.
Usually, the bedrooms are larger. The kitchen is much larger too. Extras such as media room/man cave, and higher ceilings are common as well.
We went from a 1200 square foot home (built 1890) to a 4800 square foot (built 1883) home 3 years ago. When we moved in it had 6 bedrooms, 3 1/2 baths, a parlor, formal dining room, family room, 6 fireplaces, 4 sets of pocket doors, and a large kitchen (original kitchen and original butler pantry space had been converted to a large kitchen). Since this is a cough vintage cough home, it does not have the wide-open floor plans of a modern design although with the pocket doors open on the first floor there are sight lines throughout the floor.
Already mentioned is more bedrooms/bathrooms or bigger sized rooms in general. I’ve honestly never understood the 1:1 bedroom to bathroom thing but if you have kids and guests I can see why it would be attractive. We have a 1/2 bath on the first floor, a full guest bath on the 2nd and 3rd floors, and our master suite includes a walk-in closet and full bath for our use. Guests can share a bathroom. 
We got a glaring reminder yesterday of how we take for granted our home and it’s scale when we visited our friend’s new home (built circa 1950s). It is a really great house, lots of space, an awesome basement bar and billiards room, etc., but my wife and I both felt slightly claustrophobic due to the 8 foot ceilings. We are so used to 10 foot ceilings that it felt a bit oppresive. In two of the rooms I think we would have hit our heads on the ceiling fan. In our home, we’re used to needing a ladder to change light bulbs in ceiling fixtures.
As for cleaning, it is a lot of work. Certainly unused guest bedrooms don’t get much attention. Cleaning the living spaces for us is a lot. About 6 months ago we agreed to hire a cleaning service to come in once a month and they clean everything top to bottom. This has greatly reduced the amount of cleaning we perform on a week to week basis. Of course when you have a cleaning service you feel the stupid urge to clean right before they arrive so it isn’t too messy and they think we live like barbarians. LOL
Except those “home offices” could easily be bedrooms, unless they’re not code compliant because they don’t have an escapable window or something.
But if you’re dropping millions of dollars on a house, you can probably afford a little remodeling along with that. If you can’t afford the remodel, maybe scale back from 8 figures to 7 figures?
There might also be additional amenities in the neighborhood given that it sounds like it’s a swankier house. If they entertain a lot or have guests frequently, it might be good to have a larger house.
That said, I hope they have someone to help them clean the house - that seems like a TON of house to manage.
Yep! Tested its functionality with numbers 1 thru 6. Best performance is with 3. 
Man cave, workshop, darkroom, bowling lane (always wanted one of those!), servants’ quarters, boat or camper/RV storage, potting shed, gallery, greenhouse, wine cellar, sunroom, lap pool, laundry, loft, lift for auto repair, music or theatrical performance space, recording studio, orgy room…
With the exception of bowling lane and orgy room, I’ve seen all of these in residential homes (not all in the same one).
I find that the very large once mostly have extra rooms, bigger rooms and wasted space. In my life, I have moved from 6,000 sqf, to 2,500 sqf, to 1,700 sqf. My next home will probably be 1,500 or so. There are only two of us and we just don’t need all that space. I do have a second home that is 920 sqf, and it is plenty of space too.
Outdoor kitchen and entertainment areas with fire pits and such are becoming very popular here in CA. You may “only” have a 3,000 Sq Ft home, but often you have another 1,000 Sq Ft of outdoor living space that you use most of the year, too. It’s likely to have a TV and stereo, and the outdoor kitchen has a fridge and storage, too. Some, or all of that area may be covered and heated. Really, it’s more living space than yard or garden.
I investigated…
First of all, a bowling lane is 60 ft long. Add to it the space in front and the machinery in the back, and lounge space, that’s 110 ft or so. You need about 12 ft width, so that’s 1300 sq. ft just for the two bowling lanes. And the house has to be at least 110 ft wide (or deep).
The cost of the two lanes, installed, with machinery is around 250K. And I don’t even want to think what the yearly maintenance on those lanes would come to. The lanes have to be oiled, cleaned, and the machinery maintained.
I decided I will just go to the local bowling alley instead.
Me, too, but I can dream, can’t I, or what’s a heaven for?
I know quite a few houses around mine that wouldn’t have a problem with it, at least space-wise. And $2mil houses aren’t going to balk at a $250K addition for a hobby.
The gym and offices can probably be converted into bedrooms pretty easily.
I thought a bedroom was just a room with a closet. So as long as there is a closet, you’ll be able to list it as a bedroom when reselling it.
You’d probably be interested in something like this: https://www.youtube.com/watch?v=xawputDTx-M&feature=youtu.be