Since I'm not on a Mac I don't know how Pages shows the variants. I also don't know if you have a full, paid, package for Zapfino, as I do, or the Mac system version. On my system the variants show in the dropdown below the font name, and there are four differnt listings for Std and Pro versions to get all of the variations.
If you don't see all of waht you should by scrolling through the list, try deleting all adobefnt*.lst files, where * is a two digit number. If that still doesn't solve it, try a utility like cocktail to clear the font caches.