Plot a path to Hell's Canyon via the palouse. The stretch where Highway 95 descends to the Snake river is something you gave to experience for yourself. For a longer trip, head out to Idaho and see Craters of the Moon.

Wildflower season is very brief in the high alpine meadows. A week can make a big difference and it really depends on when the last bit of snow melts. Late July could be great or a bit early but after Labor day is definitely too late.

I'd pick late July/early August for the statistically best chances of a good time. Summer up there is short (that's part of why the plants are so delicate). Melt-out at Paradise is usually early to mid July, and autumn weather starts around Labor day, sometimes sooner.

Try to stick to trails and rocky surfaces. If you're committed to meadow-stomping, find a spot that's already worn bare from others rather than trampling healthy plants.

https://www.nps.gov/mora/planyourvisit/wildflower-status.htm

https://lnt.org/why/7-principles/travel-camp-on-durable-surfaces/

Scintillation causes blurring of images over distance. The mechanism is that rising bubbles of warmer air act like lenses. This kind of lensing is what causes stars to twinkle, and also the "heat shimmer" you might see above a hot roof or hot pavement.

Scintillation is generally weakest in the morning when the ground is cold.

They can usually plow and keep it open at least to vehicles with chains, but at some point they'll have to close it for avalanche risk. Keep an eye on the avalanche forecast https://nwac.us/