|"Design Modern" graphic by Eric McGrew|
One inspiration that I have for these very simple designs is a designer who goes by Genís Carreras. There work, to me is truly inspiring. They have a wonderful portfolio, and have been featured on a number of sites. Not to mention the numerous clients they've worked with. However, you need to stop by their site and see it all.
If you want another awesome illustrators site for contemporary designers of the retro, simple illustrated style, you should check out Grain Edit too. This site could keep me occupied all day. So, take a moment and check em out. You will easily find art and books that will fit in nicely with any mid-century/retro themed interior. Plus, you'll get the opportunity to support some of the lesser know folks in the design industry.