When I was a kid, when we drove to Chicago, we'd visit the downtown Kroch's & Brentano's which (at the time) felt HUGE. I'd find Michael Moorcock, John Wyndham, and Fritz Leiber books I'd never heard of (no internet back then). A treasure trove every time.
I miss big bookstores. As a kid one of my favorite things was to go to Borders with my parents in the mall. I'd bum around the fantasy section checking out all the new titles while my dad looked for obscure German language lit with a brief duck in to the music section.