While not nearly as big as Scottsdale Fashion Square, Kierland Commons is a good eating/shopping destination if you are in North Scottsdale. If you are staying at the Westin, you can easily walk, drive, or take the free Westin shuttle.
The design and layout tries to evoke the idea of a small town center with streets running through the mall. It's compact enough that even old folks or people with kids can walk around the whole thing without feeling overwhelmed (assuming it's not too hot). The stores are all mid- to high-end with a range of things from fashion (Guess, Michael Kors) to home goods (Sur La Table, Crate and Barrell), and the restaurants range from family friendly chain restaurants (Cheesecake Factory, P.F. Chang's) to local restaurants (North, Greene House) to high end steak/fish house (Mastro's Ocean Club).