Yosemite/Kings Canyon/Sequoia “must do” advice sought

Without a camper you've got more options, especially in Sequoia. I'd do a drive up to Mineral King. This is where I grew up (tent) camping for the most part. The drive pretty much stinks, narrow road and lots of turns, but it's worth it once you get up there. Really beautiful. You cannot get there with a trailer so I'd take advantage. There is a resort nearby called Silver City that has a restaurant.

Since you're staying in Three Rivers, be sure to get some ice cream at Reimer's Candies :)