Now that I think about this, would the post office have trouble reading such an ornamental script? If this is the case, can anyone reccomend a complementary serif?

The font used for the script looks like Citadel Script. However, I agree that this would not be appropriate for addressing the envelopes. My suggestion would be to use a legible Italic face from a serif font, or else a formal serif font (preferably not Times ;-))

What about using a complementary sans that breathes
a similar atmosphere, something like Engravers' Gothic?

Thanks Mike, you script hound.

Engravers' is nice. I was also looking at some high contrast extended faces. However, both ideas were nixed out. "They look like a business letter!" At the moment, they like Snell.

... which is not very appropriate for addresses neither IMHO.
Try to talk them out of these curly scripts, or you'll be one
more victim of a postal drive-by shooting! This is serious!

You could also go with one of the Engravers fonts like AT Classic, or AT Burin. Both from Agfa.