The best invitations are engraved on paper made from cotton. When you are at your stationer selecting your invitations, feel the papers. You'll be able to tell the difference. Unlike wood-based papers, cotton papers last forever, so your invitations will be treasured keepsakes.
Ecru is much more popular in the United States, whereas white is the color of choice in Europe.
You'll want to choose a relatively heavy paper. Better wedding papers are usually 40-pound papers. Wedding papers can be either plain or paneled. A paneled invitation has a blind embossed border. As a general rule, script lettering styles look better on an invitation without a panel.