When we built my mom's house behind ours 14 years ago, she wanted one bedroom and bath, a kitchen, laundry and garden room. The rest of the house was about 18x24 with floor to ceiling bookcases on three sides. She's almost 90 and STILL buying books, although now she tries to give them to her children :-/
We also have a storage area in the basement that has not been finished. It’s approximately 10x24 feet. Hubby is building a root cellar under a two car garage sized shed.
He is going to clear out our current garage of his concrete finishing machines, generators and stuff so we can park our cars in the garage. He’ll also clear out the basement storage area—I am dreaming of additional pantry and bookcases in one half, and a spa/bath on the other side. We’ll see what we negotiate. LOL