Trail of a Hundred Giants is a Walmart Parking Lot on holidays. But it is worth a stop by in you are in the area. There are several other Sequoia Groves in the area too.
Here is what I would do. Go see the Giants. Then drive to the Lloyd Meadows Trailhead and hike down to the Forks of the Kern into the Golden Trout Wilderness. Do your 3 to 4 day loop there. Wilderness Permit required. If you fish, bring a pole always good fishing on this section of the Kern.
On your trip back, stop by Lower Pepermint Creek campground. We will be in the big white tent trailer. It will be our base camp for a week. If we are at the campsite, we will have a cold beer or Margarita available for you. We go there every 4th of July for a week or two, because there aren't many campers here. My wife doesn't backpack, so we do day hikes in the area.
I will give you directions to the Kern River Slides for your drive back toward Johnsondale. You can stop there and refresh.
Kern River Slides