Chris,
Right! I have found that someone local who is experienced and knowledgeable, who is willing to share their expertise on a particular topic can be very motivational. Of course, the field trip can reveal some aspect that is otherwise unavailable to students in the classroom or laboratory setting. Both activities add to the students awareness about the profession they're training for. Sometimes, a student will really buckle down with their studies after an especially good guest, or out of class experience.
Barry Westling