I have been thinking this same thing (great minds, ha, ha?) My list:
High waist trousers and jeans: After all of my recent grousing, I discovered Mango has some really on-trend silhouettes—and on sale!
Along with above: Dark pants in many different fabrications, lengths, leg shapes. For example, I have a nice NYDJ black flare knit pant for fall/winter/spring casual, Talbots lined black wool straight leg for winter workwear, and two light weight black crops (one straight leg, one flare) for spring summer—unless I wear them with tights and boots in winter, which I sometimes do. I could use a black three-season weight full-length dressy flare.
Some shorter-length sweaters, maybe even with welted bottoms.
Midi dresses if I need more (I bought three summer and three fall/winter/spring midis from Boden). I would be willing to go shorter and asymmetrical ala Eileen Fisher if I surrender the waist, but with a waistline, I am loving long, fuller skirts in fabrics that collapse back onto the body. I`m loving the full-on seventies sleeves, too!