The Casa Marina Ares is one of Key West’s most desired areas.  This neighborhood leaves you with a very short walk to the beach and you can bicycle to the Duval Street restaurants, shops and boutiques.  Generally speaking the homes are larger, the lots are larger and the price tags are larger.  The Casa Marina Area was named after the Casa Marina Resort which was the first hotel to open in Key West and was built by Henry Flagler.  Henry even had a home in the neighborhood as well.  Defiantly worth a look.
The Casa Marina area takes in all the neighboring streets to the Hotel (within a 4 to 5 block radius)