Seattle Pinball Museum has a great, diverse lineup of games, though condition can be inconsistent. They probably have about 40 games.
Full Tilt in Ballard has about 13, but basically all in good shape. Basically Bally/Williams DMDs and a couple Sterns. Both good choices. If you do Full Tilt, MAKE SURE you do the Ballard one. The one in the university district just has a single arcade game.