The transition to retirement is an interesting one, although I'm still half in and half out so my wardrobe is in a total state of flux right now.
I've currently been assembling a smallish capsule of wearable, every day clothes as a starting point for a retirement wardrobe. And I'm forcing myself to not put things into "wear for good" vs. "wear around the house" categories anymore. It's nice to change into comfy clothes after a day in heels and suits, but, when your down time is all the time, you can get into wearing those ratty, comfy things all day, every day. I've invested in a couple of full coverage aprons to keep my cashmere and silk looking good even if I'm just doing things around the house. Both fabrics are quite washable if you treat them with a bit of care.
Currently, my retirement capsule consists of three pairs of pants (jeans, cotton, light wool), two skirts (denim, cotton), six or seven tops (silk, linen, cotton), four sweaters (two pullovers, 2 cardigans), a silky bomber jacket, a leather moto jacket, a trench, and a utility jacket. My footwear is mainly sneakers and booties. I can work some of my office wear into this capsule for more variety. Much of my capsule came from my closet, but I did buy a couple of items to help pull things together. Ingunn's wardrobe posts were a big inspiration here--THANK YOU INGUNN! I'd definitely suggest checking out some of her posts.