My best advice is to treat buying a fun but basic item like booties just like buying a basic pair of pumps.
First, choose a color that will match tights and the majority of your skirts and pants - preferably black or brown - whatever you tend to wear more. Either color goes with denim.
Do you like suede or leather? I prefer the look of suede over leather, but it has to be treated very carefully, so that is a consideration. You will also want to purchase a bootie without a lot of decoration. The less embellishment on them, the more versatile they will be and the more outfits you can wear them with. Sounds like you want to make them an investment piece, so we want to make sure you get a good return on that investment.
I suggest buying booties without a cuff or ruching, both of which can make your ankle and calf look thicker. The sleeker the transition from leg to boot, the slimmer your leg will look.
Open-toe booties or ones with cutouts are trendy, but not practical for the cold, of course. Even with tights on, who wants soggy toes?!
Nordstrom - Enzo Angiolini 'Kaleb'
Zappos.com - Joan & David / Hartman
The cuff on this one does the opposite of a thick horizontal ankle cuff. It will actually make your leg look longer and slimmer!
Or you can throw caution to the wind and go for some serious shoe candy!
Agh! To die for.....