Leaving your gps on all the time runs your battery dead faster. Instead why not download Sms Gps Enabler off the market. You can send a text message silence ringer, and then one to activate gps, as well as many other features. From there I would follow with where's my droid as you did. I also have a pattern lock set on a 20 minute delay always. I think it unlikely that a theif would manage to steal my phone and know to go into my settings to deactivate the lock before the timer was up. This way, they can't do anything with the phone if they can't break the lock, so they would never see the text messages being sent. Also, I'm not sure if its the same in a place where coverage is readily available, but network location is terrible in the rural community where I live. It's about 3 miles off on average, so it's basically useless here.
Sent from my rooted D2G
Sorry, that's not true. The only tine it uses battery is when the gps is actively in use, for example let's say someone on latitude wants to see whare your at. Then yes, it would use some juice but unless you have something like this going on constantly it won't use that much battery.