Dauphin Island is both a small town and an island on the Gulf coast of Alabama not too far from Mobile. If you're looking to escape from the city for a few days and just kick back on the beach, then Dauphin is definitely a good choice.
As far as the beaches on Dauphin island go, they're not the absolute best you can find in the state. That honor would have to go to the Gulf Shores area. However, the beaches on Dauphin aren't bad: the sand is soft and the water is pretty clear for the gulf. The beaches get a bit narrow at times, but thankfully Dauphin Island isn't usually too crowded.
In terms of things to see, I have two recommendations: first, spend a day checking out Indian Mound Park. Apparently, Dauphin Island was inhabited by Native Americans who built mounds in the area and you can still see them today. Plus, the park is beautiful and makes for a great place to clear your head. Secondly, check out Fort Gaines, a Civil War-era fort coastal for which you can still visit today.