https://www.usatoday.com/story/travel/columnist/hobica/2017/...
What makes a huge huge difference is humidity. I get off a Denver to narita 787 feeling like it was a long Colorado to California flight, whereas a SFO to Narita flight on a 380 or 747 wrecks me.
This was a radical design decision for Boeing because bleed air usually has three key functions: it is hot enough to cause toxic ozone gas to decompose, it is at high pressure so can pressurise the cabin and it is hot so it can heat the cabin. Without bleed air Boeing had to do all these things with new components, they have an ozone filter/catalyst, an electrical compressor and a RAM heat exchanger to heat up the air (basically slows down the air increasing its temperature). The system is more complex but according to Boeing uses less energy [1] and makes servicing the engines easier.
For passengers, external air contains more moisture than the bleed air (air becomes less humid if it is compressed and heated) so the inlet air humidity is around 7% compared to 2% on other planes. But this is still less than the humidity in a typical cabin which is about 10 to 20%. Some of this is residual moisture that is recirculated but most is from passenger respiration and transpiration [2]. Even so the higher inlet humidity coming in can significantly slow down the loss of moisture over a long flight. In addition VOCs and other bleed air contaminants are minimised [3] which Boeing claims means we feel better after a long flight.
[1] http://www.boeing.com/commercial/aeromagazine/articles/qtr_4...
[2] http://webserver.dmt.upm.es/~isidoro/tc3/Aircraft%20ECS.pdf
[3] https://www.faa.gov/data_research/research/med_humanfacs/oam...
Denver's altitude also means a lower maximum takeoff weight. Perhaps less cargo/passengers = faster luggage / more empty seats?