I'm from Detroit. We have a decent art museum, but nothing this awesome.
The Carnegie Museum houses two very nice museums. Natural History and Art. The Natural History Museum is very impressive and it's cool knowing that all the specimens belong to the museum and they aren't on loan from some hoity-toity New York museum. It's not huge like the Smithsonian, but it's certainly cool seeing real dinosaur bones. My accompaniment had to stifle all my Jurassic Park "Mr. DNA" references.
The art section is also quite impressive. I personally still prefer my Detroit Institute of Art, but this museum is still nice. I got a little confused about how to walk around. I prefer my museums in chronological order, not cool to less cool, which is what this seems to be. The modern art is very cool, but after being at the Warhol the day before, I had my fill of high-concept stuff. There's quite a bit of Impressionism, which by scientific fact all women love.
This is great way to spend a long afternoon and there's plenty to do in Oakland afterwards.