I keep mine in the Apple charging dock next to the bed, and I used to use it as an alarm clock using the Nightstand app. But the phone won't do the iCloud nightly sync with the Nightstand app running (the phone must be charging, on wifi and on the lock screen), so I'm using my old BlackBerry 8900 for a clock while the 4S in charging in it's stand. That way the 4S is still available in case we get a late night emergency call.
I was also somewhat concerned that continued use of Nightstand could burn into the display after continued use, and I did have the display of my Samsung Galaxy I burn in by using an alarm clock app for several months, even though some "experts" said that current screens wouldn't burn in, so beware - it could happen! If you use an alarm clock app I'd recommend using one where the image moves around the display periodically rather than a stagnant image.