Doug: It depends--of course--on the type of course, students, and coverage you are
presenting, but I find that a 'typical' undergrad HET course (one that might use Colander,
or Ekeland&Hebert, or Rima, or Brue, etc. as a 'main' text) that Stigler's 'Selections
from the Wealth of Nations' (about 1/9th of the original, paperback and very inexpensive)
allows the students to get enough exposure to Smith's rhetoric, style and thought
processes without Smith becoming the entire course.
If you have the luxury of being able to devote an entire course to Smith, I guess I'd
recommend the Modern Library/Edwin Cannan edition, but here I defer to anyone who has
taught an entire course on Smith. This edition, by the way, is available in hardback also
quite cheap (about $16 on Amazon.com).
  
David Hammes