If you plan to vacation duirng the peak season in a beach resort, I would suggest buying a timeshare in the resort area where you plan to vacation. I have lived in a beach resort community for the last 25+ years and am a resale broker. I have noticed a high percentage of owners vacationing at their own resort during the peak season. This means there is less inventory available in the exchange networks for exchange guests. Since, you have school age children, I assume you will be vacationing during holidays and peak travel times. If so, buy where and when you would like to vacation; it will also provide you with a unit with good trading power.
