Better battery life?
Buy a Mophie. I got the Mophie and Zagg screen protector when I got my 5s, and I just love them. They make my iPhone look and feel like a real piece of equipment instead of a toy, and I only need to charge it after 3 to 4 days of use. I've accidently knocked it off my table onto the hard oak floor six times in the last month without any marks or breakage. It's a great combo.
I purchased the Mophie at the Apple Store, and had the Zagg installed at their kiosk just outside the Apple Store in our shopping mall.