My best down buys come from REI (Recreational Equipment Incorporated) or a similar specialized sports store. I look in the mens for the lightweight packables, as I have wide shoulders and dislike bright Barbie colours on me. They will cover your bum and a thick sweater, weigh nothing. Not inexpensive, but the sports gear looks like the fashion gear, except it lasts longer. Lots of sales right now.
Have had great luck with Lands End for down packables for self and husband, also.
Smartwool in tops, socks, and thin hats and gloves that pack easily in a pocket or daypack, is quite good stuff, I get it a little oversized if I may need to sleep in it. It layers easily, hand washes in hotels.
Silk long undie leggings work well in winter airports amd parking lots, freezing rental cars
I would love to see a Uniqlo store, they look right up my alley. Please post if you get one of their products? I would buy online with a good recommendation. Have a lot of fun!