DEN

Denver International sits on 33,000 acres — larger than Manhattan — and first-timers routinely assume it must be slow because it's enormous. It's the opposite. DEN is one of the fastest-moving major US hubs in normal weather because its concourses are physically separated (you take a train between them), which prevents the terminal-cramming you see at LGA or DCA. Security waits look terrifying visually because the queuing space is huge, but the actual throughput is excellent.

The one gotcha: weather. Denver sits at 5,431 feet with real weather variance, and when a spring blizzard or a summer supercell hits, DEN turns into a ripple-delay machine. Ground stops at DEN affect United's entire western-US network within 90 minutes. If you see even a light snow forecast, book earlier flights — the day gets worse hour by hour, not better.

Concourse-choice matters: Concourse B (United's mainline) is significantly busier at peak than Concourse A (foreign carriers, JetBlue, Alaska) or Concourse C (mixed). If you're flying non-United, your TSA experience will be measurably calmer. Also: the pedestrian bridge between the main terminal and Concourse A means you can skip the train entirely if you're on a Concourse A flight, saving 8-12 minutes.

The 4-6 PM westbound push is DEN's peak — this is the wave that feeds the transcons to LAX, SFO, SEA, and PDX. If you're flying east (JFK, ORD, DFW), the calmer window is often 3-5 PM before the westbound wave ramps. If you're flying west, aim for a mid-morning departure to avoid the crush entirely.