I am having a hard time visualizing a "side" step as the first in the waltz, other than, say, the side whisk or something similar.
You're not too far off. The "loose" side-close-close action I mentioned can range from side-close-close to side-close-side, to side-cross behind-side. The latter is a turning version of the Side Whisk.
One thing that may be contributing to your confusion is if you're imagining the figure as beginning with the man facing the line of dance. To move down line of dance with a side step, you would need to begin facing wall, or at least somewhere in that vicinity.
The side-close-side and side-cross-side are typically done on the outside of turn, while the side-close-close is more common on the inside. When on the outside, if you do step side on 3, it's usually smallish, being placed directly under the body.
This is not strict technique, but an observation of what I feel I do (and observe other people doing) simply to get the job done.
The side step on 1 is the longest step. It is the step with the least rotation, but that is not to say that there is none at all. I usually teach it as a straight side step, because the student will tend to add the right amount on his own without requiring a complicated technical explanation. But if I were to analyze the result in greater detail, then I would say that because of the rotation, this side step could possibly be described as beginning side and slightly forward, and perhaps ending side and slightly back.
it does sound like an excellent thing to show someone as an example of how the dance has changed over so many years.
True. It's also a great dance to teach to those wedding couples who insist on dancing Viennese as their first dance, after only two lessons.
Regards,
Jonathan