best science museum I've ever been to is the Oregon Museum of Science and Industry (OMSI) in Portland Oregon. Hands down. My wife and I considered having children just to have someone to take there to play with the exhibits and we don't even live in Oregon. I'd need more time to come up with a good list but I spent a lot of time there as a kid. I have memories of seeing a space shuttle there or something like it (I know for a fact I saw some orbiter capsules that they still have) but my mother and I have argued about whether the shuttle memories are real memories or not. I mean Shuttle Endeavour is in Los Angeles and that is worth a trip in the far future if you're a space dork like me.
So here's my experience: We have family near Portland, Oregon. We'd go visit every now and then each year, and part of the visits we'd stop by OMSI because it is THE BEST MUSEUM. So one year my family decides to take a trip to DC. We go to the Smithsonian. We hear that the Air and Space Museum is so cool, right? Set aside a few days because the exhibits are the neatest! We pop in, and we've already seen everything. At OMSI. Only OMSI presented everything in a far more fun, interactive, and memorable way, because it's not just a museum, it's also a children's museum. So we got an extra day on our DC trip from not needing two days at Air and Space.
i should probly give you a link
