Answer Question
One of the best sleeping pad combos for a Denali expedition to keep you both warm and comfortable while sleeping on snowy ground is the regular Therm-a-Rest Z Lite Sol Mattress paired with a long Therm-a-Rest Neo-Air Xtherm Sleeping Pad. (our recommeneded two favorite sleeping pads). Use the closed cell foam Z Lite pad on the bottom (silver side facing up) and then the Xtherm on top of that, then your Denali sleeping bag. I'd only get the smaller length of these pads if you're shorter (5' 6").
To keep the floor of your tent that much more comfortable and insulated while camping on Denali, you may also like Forty Below Tent Floor Foam.
What is the best Backpack for climbing Denali?
What is the best cold weather sleeping bag for Denali?
Which side of the Therm-a-Rest Z Lite SOL Sleeping Pad should face up, Yellow or Silver?