I have received some wonderful invitations/save the dates. And of course, I don't throw them away. I keep all, as mailed, with all elements.
Save the date.
My friend, Katie used a leaf, oak tree as her art element for her fall wedding. A tree she created was used on all of her favors. The colors were perfect.
Chi, printed back and front of velum. Tied up all elements with a red thread and rice paper, used a little piece of torn red paper on the back of the envelope in lieu of a seal, and mailed it all in a beautiful vellum envelope. It was stunning!
Invitation was printed on both sides of vellum, this is a flower image only on the back, invitation and text on the front. The flower printed on back shown through the text.