As I'm always preaching, you can find comfy heels! I proved it by staying in my Steve Madden wedges all day, (from Ross $14.99, thank you very much). Lots of standing and walking and most everyone had their shoes off by the end of the day, some smart enough to have a pair of flip flops handy.
So here's what I learned. When packing for a trip or going to an event knowing you will be in your heels all day, slip a pair of flats into your bag. So for each outfit you have you should know what heel and what flat works.