Before my father passed away my parents sold their home in Illinois and travelled full time for five years. They have been to many of the parks.
I have seen the redwood trees but I am not sure if it was at the National Park, same with the Smokey Mountains. Both were a few years ago.
Living less then an hour from Death Valley, I have been there several times and really enjoy it. There is so much to see and there are smaller parks and areas to explore also. I try to go at least twice a year. I take out of town guests there, they are impressed. The drive is relaxing and sometimes I just hop in the car and head that way. Often times I do not make it clear into the park, like I said, there is plenty of things to see on the way.
I really like this place. http://www.fws.gov/refuge/Ash_Meadows/ The first time I visited there was on an Easter Sunday. I took my mother and all of a sudden I seen a large oasis in the desert. I only thought quick sand and oases were found in cartoons. I found both there! Part of the refuge even has a nice board walk along a natural spring. Perfect for a walk.
(http://img542.imageshack.us/img542/6811/pgtv.jpg)