I've always stopped in each shop just to walk around (sometimes it's a break in AC). It doesn't take that much time out of your day. And at the end of rides you are most likely walking out through the shop anyway, just glance around.
all the shops in Galaxy's Edge
Keystone Clothiers in HS
Legends of Hollywood HS, though this one has some that is also found in Disney Style at DS (this is also a must stop shop for me)
Also at DS, I don't miss Marketplace Co-op & Tren-D
Uptown Jewelers at MK if you are looking for purses/bags.
Used to stop in Sir Mickey's but that stuff has changed a bit
AK has 2 very good shops, Island Mercantile and Discovery Trading Company seem to have a lot of great things I don't see all over.
The main thing is if you see something you want you better buy it. Do not expect you'll see it elsewhere, or it sticks around. Right now merchandise is at an all time low.