From "Early American Handwriting: Spencerian Script and Ornamental Penmanship, Volume II", the compendium of script exemplars by the Master Penman of the 19th century, by Michael Sull.
Feast your eyes on these beautiful capital letterforms! Plenty more of this kind of gorgeous stuff in the IAMPETH archives as well.
For wedding envelope addressing work, these days I never stick to straight copperplate (the script style which pre-dates Spencerian), but rather I tend to write a kind of heavily shaded script that is influenced by both Spencerian and Copperplate.
Brides tend to want more shading on the lowercase letters than was used in Spencerian. The hairlines can also be so fine that it's not great for digital reproduction...
*note: I keep trying to attach the jpeg of the scan, and when I click on "post", I'm just getting a white screen...?