I am happy we picked Atwell Mill campground in Mineral King area over Lodgepole/Giant Forest/Foothills Area campgrounds.
Atwell Mill offers more rustic, secluded, and peaceful surrounding than other campgrounds in the main part of Sequoia National Park.
The campsites are spacious, so you are not too close to your neighbors. No trailer and no RV. Tent only.
Amenities are basic: restroom, running water (but not for washing dishes, brushing teeth, or drinking), bear-safe locker to store store your food and other things with strong smell such as lotions, toothbrush, etc.
Atwell Mill is one of few campgrounds in Sequoia and King National Park that allows campfire. That's a big plus, but make sure you do your fire responsibly.
The road to go to Atwell Mill is long and winding (took us around one hour from the main road to the campground), but it is so very worth the extra miles. Highly recommended!