OP here. Thank you so much for all your great suggestions!

As I think about more this, I realized my parents, who come from Paris, will need a direct flight, and not be too fatigued by connecting flights and long car drives. There are only a few cities in the US with direct flights from Paris and only a few National Parks close to these cities.

So I thought of Seattle (10hrs direct flight from Paris), then driving west to Olympic National Park (2-3 hr drive, which is apparently scenic).

None of us have ever been in that region, but the photos look beautiful and apparently there are fewer mosquitoes? And it's not too warm in June? There is a rainforest and whale-watching, which none of us have experience before.

There is also a Paris-Denver, with the Rocky Mountain National Park 2hrs away, and it looks familiarly alpine. I don't know about the mosquito situation there in June, but apparently there are ticks.

Budget: not sure. Under 10K.

(The original trip was to visit family abroad, and does not need to be replicated. We're stuck here because of the green card process.)

Please critique and advise!

Just for the record, Michigan is lovely but it also has lots of mosquitos.

Some good suggestions already here. I'd add Carmel, CA, specifically Carmel-by-the-Sea. Comfortable weather, beach, lots of great places for hiking/walking along Big Sur Coast, good restaurants, vineyards. We've rented through VRBO a couple of times and loved it. We stayed about 2-3 blocks from the beach and within a mile of downtown.

Anonymous wrote:Green card process for some in our party requires we stay in the US.

Group of 6: teens, parents, grandparents.
Location: Domestic US, fresh air, beautiful views, hiking and nature walks, comfortable hotel or AirBnB.
Timing: June or July.
Weather: cooler, as few mosquitoes as possible!

Thank you for your help.

What was the original trip? Then we can help find domestic places with a similar vibe.

My vote based on the info given so far is Vail.

Colorado

Anonymous wrote:Santa Barbara. No mosquitoes. Not cool per se, but very pleasant warm temperatures during the day and cooler evenings (by the water, at least). Lots of good hiking in the hills and canyons and walks along the coast. Also lots of good day trips (Ojai, Solvang, the Channel Islands).

Bozeman and Whitefish, MT are also good options if you're looking for something in the mountains. In my experience, Bozeman is actually likely to be hotter than Santa Barbara, but the temperatures in both can be surprisingly variable in the summer. The temperatures in all of these places are going to be far more pleasant than in DC, though!

+1 on Santa Barbara, plus the wineries can make you feel like you're in France.
I'll also add Park City Utah and Lake Tahoe.

Glacier NP/ MT
Seattle/ San juan islands
UP- Michigan
Maine of course.

Santa Barbara. No mosquitoes. Not cool per se, but very pleasant warm temperatures during the day and cooler evenings (by the water, at least). Lots of good hiking in the hills and canyons and walks along the coast. Also lots of good day trips (Ojai, Solvang, the Channel Islands).

Bozeman and Whitefish, MT are also good options if you're looking for something in the mountains. In my experience, Bozeman is actually likely to be hotter than Santa Barbara, but the temperatures in both can be surprisingly variable in the summer. The temperatures in all of these places are going to be far more pleasant than in DC, though!

Bozeman, MT, Lassen National Park in CA, or Crater Lake in OR might work.

Alaska or Wyoming.

Maine or Michigan.

I think this will depend on how much you want to spend. Last minute tickets are going to be expensive. Will you share your budget with us OP?

I don't think Seattle has mosquitos. I love that area.

Somewhere like coastal Maine? There are still mosquitos though, and of course, it could be hot (or it could be less hot).

Green card process for some in our party requires we stay in the US.

Group of 6: teens, parents, grandparents.
Location: Domestic US, fresh air, beautiful views, hiking and nature walks, comfortable hotel or AirBnB.
Timing: June or July.
Weather: cooler, as few mosquitoes as possible!

Thank you for your help.