Hi BarbH and welcome to Cruise-Chat.
Shore excursions usually show up on the web site 6-9 months prior to the next year's cruises. Booking early eliminates the possibility of the tours you want being sold out when you request them on the ship. There is usually a 24-hour-prior window to cancel or change excursions, if need be.
As to which excursions to book, it really depends on what your family likes to do. If you take a look at the excursions currently available for your ports, you can assume the same ones will be available for the January 2010 sailing as well. Is your family looking for active excursions, such as snorkeling or kayaking? Do you prefer sightseeing by bus? On foot? Do you want a two hour excursions or a six hour excursion? Do you want to play golf? Go to an all-inclusive resort? etc.
Folks will make suggestions, but you always have to put them through the filter of your own family's preferences.