I found these sketches and drawings, both delicate and energetic, in the small Architecture + Design Wing at The Art Institute of Chicago. Not their most impressive collection, but still worth skipping work to go there today, if you can.
I posted a few of my favorites for you to check out. If you're interested in a closer look at the architects, but don't want to hassle with the whole four hours on an airplane plus a taxi ride to the museum, I've included some reading material that should be available at your local bookstore.
Double click on the photos to enlarge.
Frank Lloyd Wright
read this, you'll like it: Frank Lloyd Wright, An Autobiography
read this, you'll like it: Tadao Ando, The Complete Works
read this, you'll like it: Urbanisms
read this, you'll like it: Frank O. Gehry, The Complete Works