My suggested workaround solution is best for those who, like me, got the power button problem AFTER their 1-year warranty period expired, and before becoming eligible with their carrier (in my case AT&T) for a special upgrade deal - usually 2 years after getting the iPhone.
If you are within 1 year of original purchase, and so are still within warranty, then yes, you may want to trade in your faulty unit for a free replacement. That is, if you are confident that the replacement won't present you with other even more annoying problems - like being forced to use IOS 7 instead of 6. According to posts here, IOS 7 is plagued with much faster battery drain than IOS 6, and offers no significant compensating advantages. I've stayed with IOS 6.4 and still get 2-3 days of battery usage per charge with moderate use. So I wouldn't want to be forced to update to IOS 7 as a result of trading my iPhone 5 in for a replacement.
So in my case, I prefer to stick with the workaround posted earlier until I'm eligible for a special upgrade deal from AT&T in October. By then, hopefully the battery drain problems of IOS 7 will be fixed.
By the way, I generally carry my lightning power cord with im in my laptop computer case, so it's usually always with me. So, I don't have any problem when I need to power up my iPhone away from home or office.