I'd agree with most of what the others have posted, except for the following:
the further west you go, less pretty the water gets, due to the proximity to Mobile Bay. The water at Gulf Shores is very rarely as pretty as the water in Destin, or even Pensacola Beach. The current along the coast usually flows east to west, so the water from Pensacola and Perdido Bays also affects the clarity of the water.
You'll still have a great time there. Just don't plan on arriving on a Friday afternoon/evening as the traffic heading down 59 to Gulf Shores can be pretty bad.
If you like history/aviation be sure to visit the National Museum of Naval Aviation aboard Pensacola Naval Air Station....and if you pick the right day, you can watch the Blue Angels practice their flying...and it's all FREE!!!
http://www.naval-air.org/intro.html
http://www.navy.com/about/navylife/onduty/blueangels/practice/
The base is about 30-40 minutes from Gulf Shores.