Yes, I'd recommend making reservations as the campgrounds in these two popular California can get crowded in the summer. Summer gets into full swing at the end of May following the United States' Memorial Day holiday (last weekend of the month), but I'd still advise reserving spots ahead of time if you can. Check Recreation.gov for info and availability. Of course, once you get off the frontcountry, the world's your oyster as you can take your pick from primitive backcountry sites. More on hiking and camping in Sequoia/Kings Canyon at: http://bit.ly/gQeSkk

Outside magazine also recently published a feature on insider stashes in the area at: http://bit.ly/hdQ1Io