I find it annoying that every time my wife adds another calendar to her google account, I have to spend 10 minutes googling (!) to find some secret link that you have to surf to to select which calendars appear for sync. I'm not sure why this link is not on the first hit any time you search for this.
https://www.google.com/calendar/iphoneselect
Anyway, surf here with safari on you iPod or iPad or iPhone, pick the calendars you want to appear, then magically they will be selectable on your apple device.
Recorded for myself and posterity.
