On Isla Nublar there were a variety of offices located inside of the Visitor’s Center. One of these was labeled ‘Guest Services’. It is unknown what services this office provided exactly. However, a variety of functions at other amusement parks and zoos include (but are not limited to) Lost and Found, Information services, or first aid. In addition, they may have also planned a foreign currency exchange, given the plans for the park as an international destination. Information services provided by the office could include maps, or brochures of the park. It is at this office that a guest would most likely have been able to make reservations or purchase packages for future visits to Jurassic Park.
Jurassic Park by Michael Crichton page 97 (First Edition, Thirty Fourth printing)