Stayed right beside Union Square at the Hilton in January and was a very nice area to walk around. The square had a skating rink set up and nice atmosphere to hang out and have a coffee. There are plenty of shops for all budgets, tons of name brands from upscale to bargain shoppers. Plenty of restaurants to choose from in the area as well. Good way to spend an afternoon.
There are some shady areas near Union Square so be prepared for quite a few panhandlers and homeless people.