I wouldn't necessarily rule out places like GAP and ON. I'm 51 and I shop at GAP for certain basics. They have good prices (especially when there's a sale) for things like layering t-shirts and cardigans. I just avoid the really bright colors and anything that's too frilly or super trendy.
A lot of women here love J. Crew. I don't find their clothes are cut well for my body, but they might work for you.
I love Ann Taylor for jackets and knit tops for slightly smarter outfits, and they also have t-shirts that are a bit of a step up from basic. I think that AT Loft tends to have trendier looks and brighter colors, and the prices are also a bit lower.
You do have a great figure!