The Olympic Flight Museum's "Gathering of Warbirds" is an annual event held in Olympia, WA every June. They have a 2 seater P51 that they give rides in and the Collings Foundation will be there, followed by a stop at Boeing Field in Seattle.
In July the 3rd largest fly-in in the country is held at Arlington Airport north of Seattle.
Seafair is held at the end of August and features the Unlimited Hydroplanes (boats with turbine engines) that fly around Lk Washington at 150 mph+ and the Blue Angels. The Blues are in town the whole week before the race weekend and practice almost daily while here. My house is very near the lake and the Blues usually buzz the place for a few days. Very cool! They also have aerobatic groups, usually an F15 or 16 that does a pretty cool flight display, maybe a WW2 bird or 2, a C17 fly by, Coast Guard rescue demo and a parachute team demonstration (last year it was the USN Seals "Leapfrogs". If you live in or near Seattle and haven't been to a Seafair you are missing out!