Denali is a slightly different kettle of fish. Certainly, it's typically colder there than on Everest, but you're not in such an oxygen-deprived environment near the summit. And during the warmer months such as June and July you might get away with a very warm, new-generation, mostly leather boot such as the T-Rock Thermal from Tecnica ($340; www.tecnicausa.com). Which actually isn't leather at allit uses carbon fiber and nylon. It's pretty warm (with Primaloft insulation) and is designed as a winter climbing boot. You might also try the La Sportiva Nepal Extreme ($420; www.lasportiva.com), which has three-millimeter waterproof leather, Thinsulate insulation, and an insulated insole. It's a classic big-mountain leather boot, with the latest leather technology. To hedge your bets, take along a pair of vapor-barrier socks, plus of course full overboots.
Alternatively, just take a pair of Scarpa Invernos ($290; www.scarpa-us.com). An excellent, comfortable all-purpose plastic boot that is nearly ideal for Denali. Your toes might thank you.