How early before my flight should I arrive to pass through security for a domestic flight

2 hours is plenty of time, unless it's an international flight onward for some on board and or it is busy at the airport. Sea-Tac can be a mess at times with traffic and waiting lines.

2 hours before your flight

Depends on what Time your leaving their could be a lot of traffic so I would get their 2 1/2 hours early

I agree, 2hrs

2 hours..