After walking around San Francisco all afternoon one day last week, I had the same problem. First, go for a killer foot reflexology massage. If you can find a jacuzzi with good, hot jets, jump in and put your feet against one of them. Mint or coconut foot creme does wonders.
Flip flops are wonderful and my "shoe" of choice, but have no support and I have the same problem, but add about 12 years. The best flip flops I found that I love are made by DKNY. They have a thicker, rubber traction sole and a molded area for the arch. So comfortable...