Amy,
The ballroomdancers.com syllabus is a good place to start. You can't go wrong by using the figures there, because they are roughly in the order that people like to teach them in general. Also, you can have students look them up on the web in their spare time! (c:
Swing and Cha Cha are both very good choices for starter dances to motivate a crowd. Single swing is easier to teach in a pinch, but if you have two or three classes worth of time to put into it, I'd suggest a triple EC Swing. If you have even more time than that, you might consider WC Swing or Lindy Hop, but they require more effort. Many teachers start with EC Swing as an introduction to swing and a foundation for the other, more sophisticated styles.
Salsa is also huge these days. If you're looking to teach a more socially-oriented or step-happy crowd, I'd go with Salsa. Rumba, Samba, Bolero, etc are all nice for a slightly more serious crowd, or for people who are specifically interested in the ballroom dances. But Salsa just tends to lend itself better to group class situations.
I hope this helps.
Sincerely,
Jonathan Atkinson
