There is a useful feature in iOS that let's you track all the places an iPhone is taken within the prior month. Go to Settings:Privacy:Location Services:System Services:Frequent Locations. You will see entries at the bottom of the list. This will show you all locations visited, and the dates and times of each visit.

oh wow! that is really cool. Thanks!

Available on iphone 4s or newer.

That's awesome! My "Frequent Locations" was set to "off", so I suppose you'd have to get access to the WS phone and turn it on. Still a great feature.