I used to wear 3" heels and walk all around NYC. I was one of those women who wore sneakers walking from the train station to the office, but I'd wear the heels when we went out to lunch and out for drinks and dancing after work. Looking back, I can't believe that I did it.
These days, I wear 1 1/2" heels perhaps once a week to work, but I don't have to walk on a hard suface as much and avoid running a lo of errands after work when I have the heels on. When I go to a formal occasion (i.e. weddings), I won't wear anything higher than 2" and my feet ache for days aftewards.
So, if you're going to suffer for style, then make sure you get the rubber pads put on the bottom and I'd also suggest putting foot pads inside your shoes for extra padding.
Overall, heels are really bad for your back, etc. If you know you'll be sitting a lot, it's not so bad, but don't even think about wearing them and having to walk quickly, etc. Good Luck.