September can be a great time for a beach vacation. Beaches are generally less crowded and rates are even lower in some areas. Of course you must remember it's also Hurricane season along the East coast and Gulf of Mexico so keep that mind when planning your trip and be sure to check the refund policy.
Florida Beach Vacation -- A great area is Santa Rosa Beach, especially if you are looking for a beach vacation away from much of the hurried pace of life. Not too many high rises and several great houses to rent directly on the beach with the Gulf of Mexico as your backyard. Most of the houses are larger rentals but you can find a cozy 3 bedroom directly on the beach. This is the location I personally have traveled to several times...due to it's proximity to my home. Leave a comment if you have any particular question regarding this area.
http://www.visitsouthwalton.com/
California Beach Vacation -- Capitola area seems to be a great start to a beach vacation on the West Coast. Rocky, pristine beaches offer picturesque views. Rental rates right on the beach are pricey but many boutique hotels fill the area with great views of the beach.
National Hurricane Center http://www.nhc.noaa.gov/index.shtml?epac
