It's probably best from July 4 through the end of September and October. It doesn't really get much summer until July. June can be a warm month, but it doesn't happen very often. We don't ever really get the heat. We get below 30 and above 90 about three times a year. It's very temperate, but it's also very marine-like. We're very close to the mountains, so saltwater and freshwater fishing are big. You can do most anything here.
Advance booking is the best way to get cheap flight to Seattle. Book 6 to 8 week in advance to grab cheap flights. Airlines such as US Airways, American Airline, United Airline and Delta Airlines offers great discounts on airline tickets. From the airport you can use Central Link Light Rail, bus, the inexpensive way to move around. Taxis service, Ferry or Water Taxi, and Monorail is the best way.