Advice: Keeping Customers
The Club
The advantage of doing this is you get loyalty from these people. They will spread the word for you, as long as you don't annoy them. Give them the option to 'unsubscribe' from your mailings. From a list of 100, if you end up with ten very loyal people, that's ten people selling for you. Why not offer them incentives to sell for you, perhaps either cash, or vouchers against future bookings.
You need to make it worth being in your club. You have to give it value to the customer, not just for you to bombard them with sales, sales and more sales messages. Think how much it would annoy you.
Why not offer a free week (during a quiet period) that you auction for charity to your customers, or do it as a free competition to the person who refers the most people to you in a year. Make it a worthwhile prize. Remember, the more you give them, the more they will do for you.