What I show through in the telescope will obviously depend on what's in the sky that night. This changes in several ways.
First off, since the Earth orbits the Sun, what we can view will be dependent on what portion of the celestial sphere the Sun is blocking at that time of the year (in other words, what's up during the day). On a nightly basis, this changes very slowly. But as we progress through the seasons, what we see will inevitably change. Particular constellations (and obviously the stars in them) are only visible in particular seasons. For example, Orion is a "winter" constellation because it's highest above the horizon at night during the winter months. Meanwhile, in the summer, the three stars that make up the "summer triangle" are high in the sky. Some stars are visible year round. This will change depending on your latitude.
On a much shorter period is the moon. Since the moon orbits the Earth about once a month, it goes through a full lunar cycle in that time (for nitpickers, it makes a full orbit of the Earth every 27.3 days, but a full lunar cycle is 29.5 days due to the difference between the siderial and synodic periods). Thus, while the season might be the same, and therefore the stars look pretty similar, the moon will change on a nightly basis. Generally, star parties try to avoid the moon. It's very bright and that excess light tends to wash out the sky. However, if we want to view the moon (as we often do for public star parties since it's magnificient) it's best done when we only see half of it lit. This is because the sharp angle the sun makes near that cutoff (known as the terminator) causes the mountains and craters to have long, striking shadows increasing contrast and making it much more interesting.
We also frequently view planets. What planets are visible depends on where they are in their orbit. Because they move, that means that what planet is visible at a certain time in one year, likely won't at the same time the next year.
So now that I've given a quick breakdown on why we showed off what we did, here's a list of things I might have shown you: