I have arthritis which makes my feet lumpy and sore, and the medicines make me susceptible to infections. We wear Tevas where we will get wet and sneakers otherwise. I always carry a little first aid kit with moleskin in it, and just put it right on whatever spot is getting sore, it will usually stay on for days. I also have found it useful to specifically check the kids' feet. Usually they won't tell you there's anything wrong until its a full-blown blister.
I actually researched my walking shoes and ended up with a pair of Nike Airwalk shoes, although New Balance is supposed to be good, as well. I have been very happy with them, they are very light but supportive. I also just noticed they are getting worn out!