Reddit reviews Empire of Shadows

There's r/yellowstone and r/grandtetonnatlpark subreddits.

Bring a good sun hat and sunscreen. You burn a lot easier/quicker at high altitudes. UV index can be quite high at times so protect yourself from the sun. It can/has snowed every year of the month in Jackson (even July), but it rare. You'll want gear for hot dry to rainy cold to very cold snow/hail. Summer thunderstorms are very common in the summer, always have a rain jacket when out hiking and make sure you understand how best to avoid being struck.

I just bought this book a few weeks ago, but haven't started reading it. Might be good for Yellowstone History. https://www.amazon.com/Empire-Shadows-Epic-Story-Yellowstone/dp/1250023203