This couple is from the San Francisco Bay area and decided to use a photo of the two of them with the Golden Gate Bridge in the background was what they wanted for their Save the Date card.
Here is the front side of their card:
It gives a happy feeling of them looking back from a beautiful location.
According to what they have on the back side of their save the date card, they are looking for a response to help them plan how many formal invitation they will need for their wedding.
That is another good use of Save the Dates.