SEA

Sea-Tac is Alaska Airlines' home turf, and roughly half of all departures here are Alaska mainline or Horizon regional. That has non-obvious consequences even if you're flying Delta or United: Alaska's morning banks (5:30-7:30 AM to Southern California, and again to Hawaii) create passenger tides that overflow the shared security checkpoints. If your Delta flight is at 7:30 AM, you're competing for the same TSA lanes as everyone flying Alaska to LAX.

The N/S security dynamic matters. The North checkpoint is closer to Alaska's main concourses (C, D) and gets crushed at morning peak. The South checkpoint (near gates A) is often 10-15 minutes faster during those exact windows. If you're on any airline in the A gates or willing to walk, taking South is a free time savings.

The under-appreciated Sound Transit Link light rail runs from downtown Seattle directly to the airport for $3. It's slower than a taxi in no-traffic conditions, but it's dramatically faster during Seattle rush hour — and unlike I-5, it can't get stuck. Frequent flyers here almost never take rideshares to the airport during weekday commute hours.

The Sea-Tac evening wind-down (7-9 PM) is one of the more peaceful hub experiences in the US. Alaska's late-evening bank pushes the last Hawaii and California departures out by 8:30 PM, and after that the terminal genuinely quiets. If you have a red-eye connection, this is a great hub to be stuck in.