Hi Jen,
What fun you will have.
I have done a few of these with school kids and random adults, and it is always a great buzz.
And don't worry about what to say, it comes naturally.
Get them to ask any questions.
Talk to them about looking through a time machine, and as Mark suggested re Alpha Cent.
I always found the biggest WOW comes from Jupiter or (especially) Saturn.
And for some reason, when asked, they always seem to want to look at Uranus.
That reminds me, you may need a step ladder if you have height challenged customers to accommodate. Or height adjustable viewing chair.
Throw in your best Nebula (M42, M17 or Eta Car) [although some will complain they can't see anything for the clouds !

]
Your best galaxy (Cent A or Sombrero)
Your best Cluster (47Tuc or Omega Cen)
Also, it seems to be popular to show the Jewel Box and ask how many different colour stars they can see. (Then explain what the different colours indicate about the "hotness" of each different star and liken it to how metal changes colour Red-hot > white-hot > blue-hot)
BTW:
Make sure they know NO MASCARA!
Have Fun.