Why do your kids want to go back to DEL? If it is the beach, then there are plenty of beaches like Huntington to visit. If it is the hotel, bribe them with another hotel.
It's funny about Yosemite. I have the opportunity to visit San Francisco a lot (DH works for an IT company and we're supposed to be based out there) and every trip I say I need to go back to Yosemite. It hasn't happened yet but I know it will one of these trips. If I were in your shoes, I'd definitely drive up PH1 after DLR and head NorCal way, go to Yosemite and try to get to the coastal redwoods.
BTW - Santa Cruz is also another cute boardwalk to visit if you do head NorCal way. There is a steam train that runs from Roaring Camp out of Felton that runs to Santa Cruz.
If you didn't have time to go 6 hours north, Roaring Camp also do another trip out through 'redwoods'. It's not quite the same as being out in the Redwood NP but it will give you a taste for it. There is a redwood grove out between Santa Cruz and San Jose.
And the other alternative might be Muir Woods, which is a day trip out of San Francisco. You'll definitely get to do the Disney Family museum if you head to SF.