Though other technologies related to Smart Phones have advanced to a large extent, the Battery technology is yet to catch-up with Power hungry devices. The result - low standby and usage times.
Though Google suggests to keep your Wi-Fi turned ON by default for improving the location services, it is something where your Phone's battery takes a hit. Keeping your Wi-Fi turned ON also means you are providing google all required information to track your movement. I have lately used an Android App call "Smart WiFi Toggler" which does a really smart job of controlling your Phone's Wi-Fi. The App basically tracks the Cell towers where you connect to known Wi-Fi hotspots. As you move far away from the Cell tower or remain disconnected from a known Wi-Fi hotspot for a predefined amount of time, your Phone's Wi-Fi is turned off. Similary when you enter a Cell tower where any of your known Wi-Fi hotspots are present, your Phone's Wi-Fi is turned on automatically.
I have found this App quite handy and you may also give it a try and explore its various features.