Find a local design store or wallpaper store that has all the wallpaper books. Plan on spending a few hours looking through the books. If you live in a major metro area you might have a large Design Center that you can visit. Many are to-the-trade only, but will allow customers to walk through and browse. These are a great place to see wallpaper because the manufacturers will have their own showroom with large sample boards hanging on the walls for you to flip through.

For example, in Los Angeles the public can walk through the showrooms at the Pacific Design Center.

Spoonflower has a great selection of
MCM designs in wallpaper and fabric:
spoonflower

Thank you, chispa. Unfortunately, we don't have any wallpaper stores where I live. I will try to visit one next time I am in Portland, OR.

Thank you, Olychick. I noticed the great designs on Spoonflower, but I don't know how the quality would compare to more traditional wallpaper companies. Have you used their wallpaper?

Thanks, cawaps. I like a couple of these pretty well. I'll keep these in mind.

Amy, I have not, but I'd look at reviews to decide. They seem to be very popular.

For our midcentury modern bathroom, we chose something maybe a little off the ranch, but we love it: Maya Romanoff Riverbed II Glacier: It gets the color right and the feel right, and I didn't really love the true 50s throwbacks. We are doing one wall, only:

https://www.chairish.com/product/2406463/river-bed-ii-type-ii-vinyl-vinyl-wallcovering-15-yds-137-m?gclid=CjwKCAiAtouOBhA6EiwA2nLKH1cWitnkNCBkZgPOpLKQZUCTyVIdzUwY7GkywNi_rio0vjVen6hk3hoCNnwQAvD_BwE