Artist Steven Thomas has created a great series of posters for U.S. national parks in the style of travel posters from the 1930-40s. If you want to encourage the artist and spruce up the look of your home or office, you can order the whole special collection (or any individual poster, of course) from Print Collection. They claim the prints are "museum quality", so it should look pretty good!
The first poster on the left shows Yosemite National Park.
The second on the right shows Bryce Canyon National Park.