There are over 40 dining choices at the airport, with a cluster of 10 or so food and drink outlets in the middle of the Central Terminal, and half a dozen at each of the Gate areas. Asian, African and Mexican cuisine, seafood, burgers and bagels are all available, along with bars and coffee shops. For a healthy option, try Café Floret, Sea-Tac's first vegetarian restaurant. There's also a wine bar, bakery and cafés pre-Security.
Enjoy a moment or two of calm in the meditation/quiet room.
You'll find it before Security on the mezzanine level of the airport, above checkpoint 3. The room is non-denominational and open 24/7.