Travel and exchange rates?

Im taking a cruise on an american ship around the med and will be paying my final on board bill by visa. i have heard when traveling abroad and paying by your card it is best and more cost effected to have the bill made out in £. any one had experience of this?
Answer
Well, a couple of things you might want to consider.i have had nice luck here...http://travel.nice helper.info/discount-airline-travel.html