With the mods to Google play services on my G3 I was able to increase my battery longevity by a significant amount. This thread is to guide and discuss as to which "services" could be disabled inside the Google play services app using "3Ctoolbox". Disabling certain services prevents Ggoogle play service from running in the background, thus, saving battery.
As a reminder, some of the services can still run after disabling them and even cause a large amount of wakelocks. To solve this, please disable the corresponding tasks in Activities, Providers, and Receivers. For example: disabling update.SystemUpdateService in the Services tab will not disable the service completely, so you must navigate to Receivers tab and disable everything that is related to it there.
Lastly, think ahead while disabling services. If you play games and use "games" app to sync them, then you should not disable anything that deals with games. Same applies to other services.
Update 5/30/15: Google play services version 7.5... here is the list of what services can be safely disabled. Perform at your own risk. I am not responsible for any damages.