I live in Visalia Born and raised here. Sequoia National Park is maybe an hour or two drive east.
Sequoia has the HUGE Sequoia trees you're looking for and they are massive. As far as I know there are no closures to getting into Sequoia. Kings I'm not entirely sure about. Fires are fairly frequent in the area so it's not a huge deal to me.
I highly recommend you go to Sequoia and check out Crystal Cave. You'll get to see the giant redwoods andbe treated to some amazing caves.
Yosemite is another option. They do have the giant redwoods in their park but i don't think they are in Yosemite Valley. Due to the fact that it's been such a dry year i don't believe many waterfalls are flowing in yosemite so you might do that another time (if possible).
If you come through Visalia and need a place to eat. I recommend Gozen (japanese), vintage press (expensive), depot (expensie), Fugazzis (on main street), Tokoyo Garden, Jack and Charlies. Cheaper dining options include Chapalas, Azule. Those the places my friends and I eat at most frequently.
Down Town or Main Street is nice clean and safe. You can park on main and walk up and down and find dozens of restaurants.
If you have any questions about the Visalia area feel free to ask.
Where ever you end up Kings Canyon, Seqouia or Yosemite all will be beautiful.