As mentioned, Road ID has a simple to use app for iPhone and Android. The service is free. The tracking is good. It has an optional stationary alert -- if it's on, it sends a warning if you haven't moved for X minutes. And it eliminates the complications of sending data from the Garmin to the phone to the friends and family. I have Garmin, I use Garmin, I like Garmin, but some people have trouble with reliable communications between the Garmin and the phone.

Get a battery case for the phone -- you want that for a long ride anyway.

(And thanks to Road ID for this nice service. I have a Road ID as well.)