Help please.
Just found out my sister and 2 nephews from Boston are coming to visit us, what do we do? The boys are 7 & 9,so wine country is out ,and they are coming mid/end of January.
We live in San Carlos and I did get tix to see the elephant seals in Ano Nuevo but I still need to plan 3 more days.Thought about Monterrey and the equarium but I thought I would look closer to home and work my way out.
Any advice is appreciated.

Try the Exploratorium, take them walking across the Golden Gate Bridge, take them to the kids playground and merry go round at Golden Gate Park, take them to any beach and let them run around, take them to Pier 39 and have them watch the elephant seals.

Closer to San Carlos, take them to Coyote Point. There's a very nice little museum/zoo combination, and if they get tired of that, they can watch the planes land at SFO.
Give them a ride on CalTrain - kids always seem to enjoy that.

I have to admit, as hokey as they are, the 7-9 year old SF fun spots are often the grown-ups most dreaded.

Go to The Wharf. Go to The Rock. Hike The Bridge. Take a ride on The Cable Cars. Go to Chinatown.

The best way to engage the kids is to do kid stuff. Don't get me wrong, I'm not saying that the best of SF is kid's stuff. I just think that we often have to concede and admit that grown-up stuff is pretty boring to the babies.

Give in and roll with it for a few days.

I think you should seriously consider the Monterey Aquarium..its really wonderful and the kids would love it.

While the aquarium is wonderful - there are plenty of fun/interesting things much closer to San Carlos. If you had a week to entertain them, I'd definitely take them down to Monterey. But w/ all the great things in SF and on the peninsula, I'd stick closer to home.