So I've seen other posts about phones dying with 40-60% battery life, but I'm seeing a projected 13-15 hours on my iPhone 6s.
Today, I've been on standby nearly 7 hours with 2:40 usage, and my battery meter is at 81%.
So this is projecting out to 13:30 usage (down from over 14 hours when it was sitting idle).
But I'm afraid it's just going to turn off at 50%, which would be bad.
As an aside, the highest-draining apps have been Facebook (obviously), Dropbox (unusual for me that it's top-5), Photos (I dumped a ton of photos in iCloud and it's been building memories nonstop), LinkedIn, and Chrome (which has really improved in the latest version 53.x).
Google Maps, Messages, Sonos, and Gmail are the next tier.