Envelope Designs

Here are some envelope designs I liked, although there wasn't an abundance of choices at first glance:

I like the top one the best. It's always interesting when a design goes off of the medium, so the viewer has to fill it in themselves. The Marvel collection at the bottom is ok - I'm not a huge fan of the colors at the top of the medium, or of the colors themselves. I'd rather see the colors on the side. Kind of like what's found here:
http://www.logodesignteam.com/stationery-design-portfolio.html

As for my own design, I need to focus on the triangle theme. I wonder how it would look if part of the design was off of the page/envelope like in the top collection.