Here's a relatively ancient blog post from Secret Fun Blog that documents the 50 best background paintings from Scooby-Doo, Where Are You? seasons one and two—and DAMN! Taken out of context, they are really gorgeous for a series we normally think of as artistically sub-par. From SFB:
The background art in Scooby Doo Where Are You? (1969-1971) is equally splendid and foreboding. The rich, painterly environment almost compensates for the clunky character animation. Ex-Disney artist, Walt Peregoy set a high standard during his brief, first episode stint as Background Stylist. But the background crew continued to churn out quality, creepy work throughout the following two seasons. Hanna-Barbera may be known for their annoying use of repeated, looping backgrounds but, as you are about to see, in this case the sublime scenery is well worth another look.
Here are just a few: