Give yourself plenty of time because there may be a line at entry and it is a slow drive to that other end of the park give yourself an hour ahead of time I would think....
The park entrance was not crowded the two days we went--1 or 2 cars in front of us--but the road to the Long House area is 20 miles, most of it winding road and switchbacks. The speed in the park is mostly 25-35 mph, and only occasionally gets up to 45 mph. And if you get behind a slow car, there are very few opportunities to pass. I would give yourself at least an hour. Also, the Visitor Center, Museum, and most other indoor locations were closed due to COVID-19.
They had tours canceled back in early July when I was there too! Lucky you. I would arrive early at the visitor center at the entrance. There's a ranger on duty that will help you.
I thought the park cancelled the tours. Check to make sure. I was there last weekend
I would plan to be there by 8:30. It's a good idea to arrive early, mainly due to the winding roads and speed limits. It was a bit crowded when we were there, although the visitor center was closed. Smart to book the tour ahead of time!
Be there when the park opens. It's big... really big.
The drive to the back of the park is a solid 45 min. I would get there an hour early because at worst you can see the visitor center/museum stuff and talk to the park ranger who is at the entrance to figure out when and where you need to be. If you have time to kill, the museum and some overlooks aren't far from the entrance. Make sure your brakes are good etc, car in good shape - there is a LOT of elevation change and very narrow roads on mountains, you don't want to have an issue in the park
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