I tried Juice Defender on both my Dinc and Charge and IMHO it didn't do anything.
Task killers hurt more than they help unless you have a rogue app.
I leave WiFi on all of the time because, as has been pointed out, it's easier on the battery than even 3G is.
Also as has been said, I set all my apps to sync no fast than every 15mins. Weather every two hours. Facebook and other apps are manual sync.
If I feel I will be away from my charger for a while, I turn off 4G.
I had a problem a few days ago (there's a thread about it) but now the battery performance is stellar as far as I am concerned.
Very happy with this phone overall which is more than I can say for the Damsung (dis)Charge (misspell intended)