You've got plenty of connection time, so the Alaska N lounge would be my recommendation, especially if you enjoy craft beer, but it requires an additional train ride from your arrival Terminal C. The seating options are diverse, comfortable, and runway views are plentiful.

If you'd prefer to park yourself close to your departing gate, the British Airways Lounge is near the S-gates (and has proper wine glasses). More duty free shopping, international vibe, lounge views are less plentiful, mostly of nearby gates and taxiway. Haven't visited the Club lounge there yet.

Amex Lounge tops both in terms of food & beverage offerings, but requires a qualifying Amex card for entry.

Enjoy your Q-Suites, and although haven't heard any issues from SEA, be warned (and prepared) regarding Qatar Business Award shenanigans.