National parks for someone who can't hike?

hey everyone,

I figured this would be a good place to ask this question since it's been bugging me. I moved to the US recently and I really want to see more of the national parks, the photos look stunning and America has so much great outdoors scenery.

But it seems like the best way to enjoy a lot of these parks is with a lot of hiking, and I have bad knees which prohibit from doing any kind of real hiking (beyond walking on flat-ish ground). So I was wondering if anyone could weigh in on whether it's still worth it going to visit national parks (or even state parks)? and what kind of activities might still be accessible to me with a bad knee?

Thanks!

BTW: I am working on the knee with a physical therapist, but it's been really slow going and I'm tired of sitting around just waiting for the day they're healthy lol