Da Vinci’s drawings are stylized just like his paintings for the time in which he lived but his collection within his notebooks have provided us with key information on how he studied art, invented things, and created great drawings.
I would be more excited seeing his drawings behind a glass case, drawn with raw material on weathered paper.

I have to disagree with you, though, about seeing the Mona Lisa in person, and I have been duly impressed by his Ginerva de’ Benci at the National Gallery.

I had the good fortune to encounter the La Giaconda on a late evening when most of the Louvre was closed, sharing the entire gallery (the old one, where you could get closer) with only 6 other people.

I was prepared to be underwhelmed because the image is such a cliché, and I’d seen it reproduced a thousand times, but I was surprised and delighted to find the opposite occurred.

Your fifth paragraph is a terrificly concise summary of what drawing was for Leonardo, Charley. Da Vinci’s justifiable fame could rest quite securely on the drawings alone.

As a scientist, engineer and painter he is interesting and his combined work in all those areas has made him the iconic genius of the Renaissance.

But, in fact, his life was full of stories of “almost”: He almost discovered the circulatory system. He almost converted his notes into a treatise on painting. He almost invented the bicycle, the helicopter, the tank, etc. He also almost finished some masterpieces.

He completed so few paintings that even during his own lifetime already he was developing a reputation as a procrastinator who could not be relied upon to see things through in a timely manner. (See Vasari)

By the end of his life his painting style had deteriorated into a creepy kind of sentimentality that seems almost perverse today (see his painting of St. John in the Louvre c. 1515/16).

I find the Mona Lisa (seen in person or in the highest quality reproduction) a pale ghost of what it must once have been. The Ginevra in Washington DC far is more interesting in terms of how the paint is used to describe the landscape of a human face.

But his drawings are the road maps of exploration in the intellectual travels of an insatiably curious mind. The mind of an artist, first and foremost.