Some of you know this one already but for those who don't, you can create a Formula URL to open with Google Maps. The drawback is that on iOS devices, it will open using the Google mobile site in Safari - it's harder to use than the Google Maps app. So after a bit of research, it was an easy fix that will now open natively in "Apple Maps" on the iOS device and Mac running Mavericks or "Google Maps" on Android and PC.
The formula is: "http://maps.apple.com/?daddr="& [End Address Column]&"&saddr="&[Start Address Column]
"http://maps.apple.com/" - this is the important bit. I used to have: "https://maps.google.com/"