Pack two pair of comfortable, well-broken in walking shoes. Each day switch to the other pair. Your feet will thank you. It is nice if the shoes can be worn with anything in your suitcase. I pack a pair of black flats and a pair of flat-soled boots, often, but sometimes a second pair of slip-ons in place of the boots. In either case, they can both be worn with slacks, jeans, or dresses. You can even switch them back and forth from day to evening.
The reason has to do with pressure points. No matter how well-fitting a pair of shoes may be, your feet rest differently within them. By switching off shoes, you give those pressure points a break. This will greatly lessen the chance for blisters or sore spots.
Again, just another simple little tip, but worth so much! Trust me. Your feet will thank you.