I had to be up in Everett today, so I decided to visit the Future of Flight Museum and take the new Boeing Factory Tour.
The Museum itself is pretty sparse for exhibits (kind of reminded me of the Steven F. Udvar-Hazy Center when it first opened) and is mostly large plasma and LCD screens with models of the planes. So a lot more information about each one. They have a P&W 777 engine, a P&W 707 engine, and an RR engine from the Comet 1. They also have a fueselage diameter from the 787 in carbon-fibre and a cabin-mockup you can walk in on.
The new factory tour is like the old one, except they take you down to the far end where you can see the 777 being built (a 772ER for KLM and a 773ER for AF) and, starting next year, the 787 assembly line will also be visible.
All in all, as aviation buffs, you'd probably enjoy the Museum of Flight more, since there are many more exhibits and you can walk inside two of them. It's also much closer to Seattle (about 10 mins instead of 30 mins).