Our last house was about 3,200 sq.ft. plus a full basement, a full 3rd floor walk-around type attic with lights, windows, and its own stairwell up to it, and an oversized garage. We had it for 22 years. At its peak we maybe used the Dining Room 3 or 4 times a year. It was down to 0 to 1 (Thanksgiving) by time we sold it. The Living Room was used maybe 2 to 3 times a year at its peak and was down to 1 (Christmas Day) when we sold it. There was a Sun Room that both the Living Room & Family Room opened to. It was never used more than maybe 2 times a year and was down to 1 (Daughter’s birthday) by time we sold it. With 4 bedrooms and 3.5 baths, we had additional unused rooms once the kids moved out. A huge house was occasionally nice but it had a lot of wasted space that we paid for, paid taxes & insurance on, and heated/airconditioned. Our current home is big enough to be comfortable when the kids come and otherwise only has the kinds of spaces we actually use on a regular basis. The only non-regularly used spaces are the 2nd & 3rd bedrooms that the kids use when they visit and the bathroom that goes with them. We got smarter as we got older.
The one thing that we did do smartly is never to have started the mortgage from scratch time-wise. Our 1st house had a 25 year mortgage and I swore we would in fact be mortgage free in 25 years. 6 years later we moved and I took a 20 year mortgage. 8 years later we moved and I took a 15 year mortgage which I proceeded to pay off in 11 years, exactly 25 years after starting the very 1st mortgage we had.