This is a very broad category. With the right design, almost any paper can be used as part of an invitation or announcement - be it as card, overlay, envelope lining or the envelope itself. Through the years, we've seen hundreds of different types of papers used as part of some very creative projects.
The papers selected below stood out in our minds in one way or another. Arturo and Lettra, for example, are complete sets of papers/cards and envelopes, and are hugely popular for invitations and greeting cards. Stardream, Curious and other metallics have, over the past decade, become the new staple of the industry. Others included below are notable for their color palette, texture, weights, printability and feel.
We also included many writing papers that make for goregous stationery. (Around here, we're currently using Frankfurt, Somerset Book and Arturo Book for ours.) All in all, we encourage you to familiarize yourself with the myriad options available to you so you can choose the right paper for your next project.