Will be going to Vegas for 4 days soon. Will be my first time there. Obviously we will be out and about for the majority of the day and the night. I have serious concerns about how to make my iPhone 5 last for over 16-18 hours a day. I don't really plan on bringing a backpack with me and my wife doesn't want to bring a purse either, it will just be me in my t-shirt and jeans, roaming the strip....so that makes things a bit tricky. Should I get an external battery case like Mophie? - Pros: No need to carry lightning connector or anything extra in the pocket - Cons: Makes phone heavy, wife can't charge her Samsung GS3 Or Should I go with an external battery pack? - Pros: Can charge both my wife's S3 and my iPhone - Cons: Need to carry charging cables and the battery pack separately...will probably end up need a backup just to carry this stuff. Any other suggestions? Looking for tips from people who have been to Vegas before.