I've stopped using the Garmin app (since it crashes 90% of the time) and Glympse and switched to Twist to let my fiance track where I am.
I like it because it gives you the ability to send notifications automatically for your departure and arrival AND it will update people following you when your ETA changes.
This app really only works on point A to point B specific rides so if you're looking for a "I'm going out riding, be back in 2 hours" app, this isn't it. I use this on my daily commutes to and from work and my fiance really likes it.
For a long distance ride I suspect you could create shortcuts for each rest area and start a new twist before leaving from the previous rest area. That could work