Well, I have to say that the Exploratorium in San Francisco is the clear winner so far. They have hours (4H+ for us), of cool demos and science related exhibits, most of which I've never seen anywhere else. If does not make science cool to others.

fun with magnetism

the slingy that goes doewn forever, cool idea

the plate turned and the challenge was to draw a square on it. I failed.

this was cool! Seeing decomposition of a rat fed to a beetle colony after a few weeks.

very nice aquaphobic plant

I had never seen termites before, cool

example of fractal-like figures in nature

you could see a live chick embryo in an egg

special cool looking fish bred by humans

grow your mushrooms at home. Yeah, I do that :)

sublimation of frozen liquid nitrogen

Since we were in San Francisco, and had paid the lovely parking fee which can go over $30 now, we walked around Fisherman's Warf and Pier 39.

$40 parking is full, great...