For those of us without £1000 to buy the Taschen book, here are some examples of what opened up the world of art and design to record covers. According to what I have read Columbia reissued a Rodgers and Hart compilation with an illustrated sleeve by Alex Steinweiss and the sales went up 892%!

http://www.alexsteinweiss.com/as_index.html

They still look amazing today. Dont forget the sleeves would have been 10"!!!