Well in my case it looks to have been entirely tied to one or more of the watch faces I had downloaded. Once I removed them I have not had the issue with Google services. That said. I am pretty sure when I got the latest update is when this all started. I should be able to have 50 watch faces that I downloaded from Google play and not have it cause a problem, its something Google needs to address go be sure. Since you're not on a nexus I can't say hold out for a week or two and you'll have marshmallow, instead I will say go through your apps and figure out which one or more are causing the problem and ditch them until the next update. Or .... Carry a spare external battery anker makes some nice affordable options. I have 2 for when the wife and I camp or travel. Good luck.
Update :
Here's the latest. Tuesday and Wednesday were my test days. On Tuesday I rolled sans Moto 360. A sad day indeed.
With WiFi and BT off I made it all day had about 40% battery left by days end. (There is one caveat - I had to put it into airplane mode to get it to kill WiFi. I obviously took it back out of airplane mode but had to toggle it to get it to actually turn off the WiFi service.
This bothers me.) Then yesterday I rolled with the Moto 360 (yay
) I left BT on and WiFi on (connected here at work) and made it to bed with 16%. Acceptable obviously cause I made it through my day, but unacceptable in the case of overall battery life.
Something is afoul in my phone and it's keeping my WiFi and/or my mobile data active and burning battery. My Android OS is eating enough battery to be in my top 2 or 3 battery stats. I am really hoping Marshmallow fixes it. If not I will factory re-set. If I am still having issues ... well honestly I haven't gotten that far. I may buy the X Pure or hell ....I may go
fruity.
May the Lord have mercy on my android soul.
)EDIT(
The phone wants to stay awake all the time (or IS staying awake all the time) I downloaded greenify and it has been able to keep it asleep (the last 2 hours or so) so we'll see.
)UPDATE(
I went ahead and got a Moto X - I'm keeping the Nexus and I am not 100% sure I'll be keeping
THIS X but already it is showing me how poorly the N6 is running right now. Really hoping Marshmallow fixes it.