I have the same battery drain issue. Before upgrading to the S6, I had the Note 3 for the past 2 years and had no battery problems at all. I'm using the S6 exactly the same way as I used the Note 3 ... it's basically in my pocket the whole time. I hardly ever text, make calls, or anything but my battery is 20% before lunch.
for the past two weeks, I've tried everything but I'm running out of time because Verizon only allows a 14-day window to evaluate a phone.
I went to Verizon the rep took my phone "backstage" for about 10 minutes and then came back to say I need to keep closing my apps ... they are the problem. Why didn't I need to do this for my Note 3? Since I left the Verizon store, my phone has rebooted on it's own 5 or 6 times.
I read the story above but I don't see any real answer. What is going on here?