Well, a little discussion I have seen is that the 4G antenna will be sucking up the juice. Turning WiFi off will help, especailly if you are in areas you know you aren't going to use the WiFi Radio.
Thing to note, the wireless will still be on, be it 3G or LTE unless you turn airplane mode on, which disables the phone's wireless in general. (No data, no incoming calls or outgoing.) WiFi is not the same as 3G/LTE for those of you who do not know the difference. WiFi is good to save data usage, but only works when you are near a WiFi source, but not necessarily good for the battery in general.
Phone Idle and Phone standby will generally have higher percentages in the long run as those will be the state that the phone will be in when not using the phone. Short of turning off the phone, you won't be out of Phone Idle or Phone Standby. Just remember, the phone needs to periodically 'ping' the cell towers or be in a 'receptive' mode to know that it has a call or voice message. This would also be the state your phone will be in prior to your apps doing its own little pings.
I will admit, I went and got myself an extended battery so I am testing how long it will run while running in LTE mode, but prior to that, it was lasting a good part of the day before I needed to recharge on the normal battery. With the extended battery, CDMA only, I was able to go a good couple of days before hitting 40% of the extended battery.
Turning off wifi has been known to improve battery life since the OG.