Go online to search for various beach facilities. Especially helpful is the website run by the Collier County Visitor's and Convention Bureau and details the various beaches and even tell you what the beach conditions are. Another website with great beach info is the Visit Florida site. This website is operated by the state of Florida and even has bloggers that discuss their favorite beaches and sites around Florida. You can even see photos taken of the beaches you are planning to visit (see Rssources).
Phone a representative from the visitor's board of Collier County at 1-800-688-3600. Collier County encompasses Marco and Naples beaches. Getting live help will definitely make it easier to narrow down what beaches you want to visit. Their travel representatives are cheery and very helpful and staffed by seasoned local residents.
Visit the Collier County Visitors Center located at 3050 N. Horseshoe Drive, Suite 218, Naples, Florida 34104. They have printed pamphlets and representatives to assist you in all your questions about Naples beaches.
Ask your concierge about their opinion on the best beaches for your family in Naples. If are staying in a condo, you can find a front desk manager that may assist you in this capacity. Most often the manager or concierge is a local resident and will know more details about each beach than a website may have. They may have more information about which beaches are more crowded or which beach is the cleanest.