I'm sure others will give you good advice on what to do and see in Yosemite/Sequoia. I've only done day trips to Yosemite a few years ago, and it's been a long time for Sequoia other than a day trip about 7 years ago to Grant Grove. I grew up camping in these areas though as I'm from Visalia originally.
The other thing I would check is make sure your length isn't too long for Sequoia/Kings. Many of the roads there have pretty strict length restrictions.
But if you want to go to the beach, you're closer to it from Sequoia/Kings than Yosemite. But be aware that it's still about a 3 hour drive. There are RV parks all along the coast in and around Pismo (Cambria, Cayucos, Morro Bay, Avila etc) but I'd guess they get filled up pretty fast.
