I keep thinking about the message that Napa is certainly not for kids. Plenty of them live here, so here are some ideas to plan a vacation that includes them in a Napa trip.
Napa Adventure Tours-electric Boat Ride
Gondola Ride at Hatt Market Place
Hot air balloon ride
Hobby car Racing in Napa Town (near Jefferson)
Wetland tour at Viansa
Tram ride at Sterling Vineyards
Cinedome Movie complex
Napa Outlet for shopping
Kayaking in the River
Outdoor movies in the Vineyards (Casa Blanch this month)
Bowling
Nasacar Racing at the speedway
Jelley Belly Tour (in Fairfeild)
to eat? why not Taylor's refresher
or Pizzeta overlooking the Valley at Auberge de Soleil
Tapas at ZuZu's
I think kids could have lots of fun in Napa with the focus on a balance of activities!

Don't forget the fainting goats at the geyser in Calistoga!

Fainting goats? Tell me more! I feel a trip coming on!

At the Old Faithful Geyser in Calistoga they have a pen full of those goats that faint if you make a loud noise. Kids like goats--especially goats that do bizarre things!

Applejaxs and Kikahead, living in SF I've never heard of some of it! My inner child thanks you so much

Not to offend anyone but these are my reasons Napa or Sonoma would not be great for kids.

When I went to the wine country, I toured the wineries. While I'm sure some of the wineries have family days or picnics, I don't want to have to listen to a guide over a talking child. Secondly, I think children would be bored stiff. Kids on vacation want to run and play and not have to be quiet. My parents saved wine country until my siblings and I were already grown and out of the house.

Sure there are lots of kids that live there. There are also lots of kids that live in Vegas but that doesn't mean it is the best vacation for them.

Again, just my personal opinion.