Tena,
Yes, motivational and inspirational are good adjectives to describe guest speaker and field trip outcomes. I think sometimes, for some students, they have only a vague idea what their career or work setting involves, and both these learning activities provide greater insight into what these employment settings offer. And the ability to ask questions from "a different resource" usually is beneficial. For me, it seems students are willing to ask a different type of question from these outside information providers.
Barry Westling