I'll be there.
I don't have much to add about restaurants or hotels, or about the camping at the fly-in. (I live far enough away to not be super familiar with the Arlington area, but close enough that I'll just return home at the end of the day and not need to camp or get a room at Arlington).
But I should add that Paine Field, just a short hop to the south, has some neat attractions. Paul Allen owns a collection of about fifteen airworthy WW2 fighters (plus a MiG-29, a B-25, a couple of biplanes... all airworthy) and
his hangar is open to the public. His lawyer is another rich airplane collector who also has an assortment of biplanes and WW2 fighters (including a P-51B with a Malcolm hood, and an F7F and an F8F), and
his hangar too is open to the public. The Museum of Flight is at KBFI, but their
restoration facility is at KPAE, and it includes the last DH Comet in the Americas, Kelly Johnson's JetStar, a Vought Cutlass,
and more. And like Mike said, there is the
Future of Flight mini-museum, where you can get on a tour of
Boeing's widebody factory.
Flying around here is great if the weather is clear. Of course, it's amazing to fly around Mt Baker or Mt Rainier. The North Cascades, just east of Arlington, are really cool and jagged (and many are right by nice flat valleys with roads, i.e. pretty safe flying in case of engine trouble). The San Juan islands are beautiful, and the water around their shores is surprisingly clear. My absolute favorite thing to do in an airplane is to fly around Mt St Helens, but that's an hour south or so, might be a little out of the way. (
See here and scroll down to the second bunch of pictures).