Invitations is the first opportunity for couples to introduce their wedding color, wedding style, and set the formality of the wedding. As a wedding decorator, I often ask my clients to bring a sample of their invitation for me to see. After seeing the invitation, I try to design the ceremony and reception to mimic the style and colors of the invitation. This is done to have a cohesive design and color scheme.
The wedding invitation is also a good starting point for designing the rest of the wedding stationary. Stationary such as save the date cards, rsvp cards, seating cards, place cards, table numbers, menu cards, and thank you cards. (Yes, there is a lot of cards for one wedding!) These cards can be done by your professional wedding invitation designer or you can do it yourself.
I don't usually do wedding stationary but I did for a recent last minute wedding. For this wedding, I made a seating chart, table numbers, seating cards, and menu cards with leftover wedding invitations. The wedding colors were lilac, champagne and burgundy. I used the back of an invitation for the table numbers, menu cards, and seating card. (The thicker paper provided some stability.) The invitation envelopes were used for the seating chart. This is a really easy DIY project to tie in the wedding colors and to make use of leftover invitations. Just make sure you have a really good paper cutter!