I call to book, as it is usually for myself and a friend that lives abroad, so I deal with the sometimes tedious "on-hold" music/info/wait times. It is hard, if not impossible, to ever talk to the same person with whom you've spoken before if you have follow-up questions or concerns. The same goes with when you email your questions. However, that being said, it is simple to sort out what they offer and what the itinerary is. What can be hard is to sort out what the optional tours that the underlying tour organizer is actually offering as far as the timing goes (fitting in with the included parts) so it's sometimes better to wait until you are there to better understand that part. So bring extra cash if you plan extra excursions NOT on the itinerary.