In the spirit of that Alaska thread, just prior to roll from SEA a few years ago, the pilot announced that our departure routing was the closest possible view we'd get of Rainier without actually climbing the thing. UA 777, sunny day, I was on the A side of the aircraft, and it was absolutely spectacular. Felt like we could reach out and touch it.

Also took a sightseeing flight to Everest one day and I had the good fortune to be in the cockpit as we were approaching the mountain and beginning our turn away from it. Those flights don't actually get *that* close to the mountain, but with a good zoom lens it's certainly as close as I'll ever get. (This one didn't require a special courtesy since the flight was for this purpose, but it was still quite cool.)