We booked several trips before we went thinking that this would be the best way to get to certain places e.g. We booked the Shangai Sampler trip only to find that Princess run a shuttle bus into Shanghai and we could have walked to the two places the trip took us within 20 mins saving ourselves $100. This was also true of other places, if you are happy to explore on your own don't book trips until you have checked out which ports of call have shuttle bus's running then you are able to make a much more informed decision. If you have booked trips online you do have the option to cancel once on board as long as this is done before the closing date which is displayed on the info on the tours desk. Hope this may help.