The sewing space that pleased me most was also the most simple, many decades ago, in a century-old house, making something out of nothing. For a sewing machine table, we fitted a piece of plywood into one of those awkward ancient closets that have hard-to-reach space on either side of the door. That dead space held shelves for storing sundries, patterns in transparent bins.
The best part of this arrangement?
I could lean the ironing board against the table and just shut the door - instantly tidy.

Today, since I sew only sporadically, I would feel strange setting aside an entire room just for sewing. I set up shop in the least-used guest room. The temporary arrangement keeps me from getting too absorbed and too messy. My biggest wish would be for a HUGE table for cutting out which could be magically stored without getting in the way. As for the rest, I think improvisation keeps the mind flexible.