As someone who's been to all 63, I think Grand Teton, Kenai Fjords, and Isle Royale are some of the best US national parks to visit in the summer.

After visiting all 63 national parks in the US, my favorites include Yosemite and Grand Teton. I think Gateway Arch is among the worst parks, though.

As someone who's been to all 63, I think Grand Teton, Kenai Fjords, and Isle Royale are some of the best US national parks to visit in the summer.