i suffered from the battery drain issue with my 2 iPhone 4S's. I found that when i used cloud backup and WIFI sync, the WIFI would continously stay on in standby mode, which was draining the battery very quickly.
I turned OFF iCloud Backup AND WIFI Sync
and this seems to have resolved my issues. Now wifi turns on when in standby.
Unsure if this is your problem?
Leave your phone in standby for around 5 minutes, press the home button to light up the screen and if you see the wireless icon straight away then you know this is your problem. You should normally see the 3G logo then it should initiate the WIFI and connect.
Has been great for a few hours now, even with Microsoft Exchange (Push Method), background apps and Siri.
Hope this helps you as it did for me. I've sent feedback to Apple and hopefully this issue will be fixed soon.
Other workarounds that may work:
Turn off Time Zone in Settings
Disable location services for reminders
Let your battery drain fully and power itself off and fully charge (Full battery cycle)
You may have discovered the problem. Since I bought the 4S never enabled those features. Never had the battery problem. After a day with full charge and about 20 calls, I still have 90% !