The Boeing plants have Tully's Coffee stands. A lot of grocery stores in the Seattle area will have a Tully's when there are a lot of Starbucks locations nearby.
FWIW, there is a Starbucks 5 minutes away from the Everett Plant in Mukilteo and several more within a 15 minute drive in Everett, Mukilteo, and unincorporated Snohomish County.
There are also a number of independent and small chain espresso stands in the area. Everett is one of the few cities in the US that has legal "bikini" espresso stands, so visitors may want to stop by one of those stands for a drink or baked good.