We saw the ones in Kings Canyon and they had famous names and were huge but there may be bigger ones else where.
Being from KY this was a new experience for me and the kids (just turning 14 at the time) and I am glad we did the 8000 mile run to the Pacific by way of Yellowstone and back through the Grand Canyon.
Now at 16 and being pulled in so many directions I am not sure they would be cool with being on the road for 31 days be we have hit 38 of the lower 48 states by RV or by car to date. They are still cool with week car trips and hotels. At 6'3" the son requires a lot of physical space and the daughter a lot of personal space and both are in short supply in a 32' MH. :)
I know the OP is not traveling with kids but to those with kids still at home work to get them out as far as you can while you can.
sremsing the redwoods are awesome and worth the trip. We really found the forest to be relaxing. Still not sure why but Monument Valley impressed me more than the great Yellowstone and Grand Canyon. Maybe it was the tour riding on a bus seat welded on to the back of a PU truck with NO seat belt. :)
We left KY with no schedule other than see Yellowstone, Pacific Ocean, Grand Canyon and the Four Corners (required by the son). The best part of Four Corners was we went through Monument Valley to get there. :)
Have a wonderful trip to the west coast and go as far as time will permit. We never plan to do it again in a RV but glad we finally loaded up and took off after talking about it for five years. The west is very different we found.