I'm currently reading Vladimir Nabokov's autobiography,
Speak, Memory. Like most of his work the writing is simple but raw and unbelievably descriptive (without being flowery). But Nabokov is intense. Fluent in English and French along with his first language, Russian, he writes in whichever language he chooses (as opposed to writing everything in Russian and having the work translated).
Even as a non-native English speaker his grammar and overall mastery of the English language is far better than mine. I'm constantly in awe of his ability to express himself and he has a knack for choosing exactly the right words.
I finally decided to keep a list of the vocabulary words I wasn't familiar with, starting on page 40. Between pages 40-47 I listed no fewer than twelve words - some I feel like I know in context but wouldn't be able to use them properly on my own, and some are just unknown to me.
So in seven pages I noted the following words that need looking up:
simulacrum
ultima
coevals
assiduous
prodigious
mycologist
stipitate
pilei
viscid
serfage
hoary
nomenclatorial
It's kind of nice to get waist-deep in a long, absorbing, thoughtful book and nice to expand my vocabulary at the same time.