Upperclass students have even more to gain than first-years by participating in Faculty Night.
Once you've been here a while, people will expect that you know much more about Stanford and that Stanford will know a lot about you. These "people" might be summer internships, research opportunities, prospective major departments, even friends and family, and they will be asking for recommendations of many sorts. You are now much more sophisticated in the kinds of questions that you can ask and in the background knowledge that you can bring to a conversation with a faculty member. You can draw them out about their research interests and their career path, and you will each know the other much better afterward. When someone asks you about a topic that you are interested in, you can respond saying that over dinner you learned about it from well-known Professor X. When you need a letter of recommendation, Professor X will be able write a much more convincing letter because she knows about your work on AIDS or solar car or the Stanford Storytelling Project.
You can invite a professor by yourself or with a group of friends with similar interests. Check with your Academic Advising Director and house staff about what event your residence may be planning--the dining halls typically do one or two faculty nights each year, while other houses may arrange smaller events. Just don't miss out on this opportunity to connect!