Thanks, guys. I've been trying to figure out if my particular iPhone 6 has an issue with the battery or if what I'm experiencing is normal. I've turned off every feature that I can (and still maintain basic usability). But compared to my 4th gen iPod Touch and my iPad Mini Retina, the iPhone's battery life is dramatically lower. Talking on the phone doesn't hurt it at all. Texting doesn't deplete it too bad. But any sort of prolonged web surfing or app use seems to kill it within about 3-4 hours. When I'm off site now (or at home), I try to make sure I have my iPad with me if I think I'll need to web surf or use an app for any length of time. I have to be able to talk on the phone and can't afford to have a dead battery or be tied to a wall charger.
Time for a battery pack case or a trip to an Apple store, I guess.