Wow, battery life doesn't even enter into my equation. I keep my phone on 24/7, and when I am home, it's plugged in and on. Some days, that means it gets plugged in at 7PM after being off the power supply since 8 AM, and others, it's on battery power/plugged in on and off all day. But, I've left in on all day/night, uncharged, and still wake up the next morning with at least 40% charge. On a typical day where I am out of the house most of the day and it's on, connected to Bluetooth for 2-3 hours, I rarely see less than 60% charge. Now, I don't use my phone for videos, GPS, or any of those other charge zapping things, but I do look on line, text, check email, as well as use the phone.
I really felt Bluetooth was worth it in the past couple of months when my son in CA called me and I was driving fairly long distances for work. He has no concept of when it might be good to call, and I was able to have very meaningful conversations with him; sort of like when it used to happen when he was in the car with me.