For a few with successful re-dos:
El Diente->Mount Wilson->Wilson Peak, summer 2016: Not enough snow on El Diente's north face, I got a few hundred feet up the loose, crappy gully with plenty of rockfall around me and turned around since it was too slow and dangerous.
El Diente->Mount Wilson->Wilson Peak, summer 2017: Turned around at Rock of Ages saddle in early morning darkness. I was just too tired to give it a real shot so I called it.
Wilson Peak, El Diente, Mount Wilson, summer 2018: got each peak individually by the standard route, south slopes, and southwest slopes respectively.
La Plata Peak, winter 2016-17: Extreme depression and suicidal ideation. I got to the bottom of the Class 3 headwall on the winter route and realized I wasn't thinking clearly and would probably hurt or kill myself, whether unintentionally through poor decision making, or simply off myself intentionally. In a moment of lucidity I turned around. I got this one a few months later when I was more clear headed, then did Ellingwood Ridge in 2018.
Little Bear Peak, April 2018: I did the Blanca-Ellingwood traverse and planned to do Little Bear the next day, but it rained overnight and everything was coated in a thin layer of glaze ice. Pretty easy choice not to climb. I soloed it in early summer.
North Maroon, 2018: I climbed Maroon and didn't want to solo the traverse so I descended Maroon and got to about 12,500' or so on North Maroon's standard route when it began to rain. I turned around and went back two days later to get it successfully.
Kelso Ridge November Grid Slot: Massive blizzard on my first attempt. Bad enough that I couldn't stand up and couldn't see more than a few feet in front of me. I still somehow made it to the bottom of Kelso Ridge before turning around and navigating back to the road with GPS. I went back a week later and got my November grid slot.
Mount Hood, Oregon, Pearly Gates, April 2018: It rained and/or blizzarded every single day for nearly two weeks straight. We went south to Mount Shasta, which we failed on (see below), then came back and got Hood on my final day in Oregon.
Mount Audubon, February 2017: Southeast ridge, group size too large.
Mount Audubon, February 2018: Southeast ridge, winds so high we couldn't stand.
Mount Audubon, December 2019: Standard route, winds so high we couldn't stand. I went back later in the month and got it for my 100th ranked 13er for the calendar year.
(Yes, the easiest peak on this entire list took me four goddamn tries.)
Unsuccessful climbs with no successful re-dos:
Island Peak, Nepal, 2016: Got to Island Peak base camp and had severe altitude sickness including Cheyne-Stokes respiration. I went to sleep, which I probably shouldn't have, and woke up feeling OK. We climbed to about 19,000 feet and the breathing issues came back, so I decided to turn around. I thought I was going to die or be helicoptered out of there.
Mount Rainier, Washington, Kautz Glacier 2017, independent trip: Our tent blew away in 60+ mph winds and flew off the Turtle Snowfield and was never seen again. It was getting dark and I immediately had the team turn around instead of try to survive the night out.
Mount Rainier, Washington, Liberty Ridge 2018, independent trip: Difficult glacier conditions on the Carbon Glacier took us into a massive crevasse field on the northwest side of the glacier and we ended up not being able to safely navigate out of it onto the ridge. It was also extremely hot and snow conditions were absolute crap. Turned around. Bonus success: Mount Baker's spectacular north ridge a few days later.
Aconcagua, Argentina, independent trip: Went to the wrong camp just following the people ahead of us in a blizzard instead of thinking for ourselves, which blew our itinerary. Documented here:
https://www.14ers.com/php14ers/triprepo ... trip=18570.
Pico de Orizaba, Mexico, April 2018: Turned around at the base of the glacier (~16,000') due to lightning.
Massive Mania, summer 2018?: Got onto Massive's north ridge early in the morning and the sky had shifted from night darkness to green to yellow to pitch black with torrential downpour, hail, and near constant lightning. Obvious bail.
Longs Peak, February 2018: Absolute garbage snow conditions in the Trough. Got to maybe 12,000' or so and we were swimming in chest deep powder. Big ol' bail time.
Longs Peak, February 2020: Extreme winds slowed us down. We went a little ways past the Keyhole just past noon to scout it and turned around. Bonus success: Bierstadt, Evans, the Sawtooth, "West Evans", and Mount Spalding the next day.
Mount Shasta, Casaval Ridge, April 2019: Extreme winds past the "technical" traverse portion of the ridge. Forward progress was painfully slow so we bailed.
Close calls:
Mount Yale, East Ridge, Spring 2016: Got summit fever and pushed past safe snow conditions to reach the summit. Triggered an avalanche while descending, alone, on a route I don't think I told anyone I was doing. Didn't get carried very far but learned right then and there not to push snow conditions too far and always tell someone where I'm going.
I'm sure there are others but those are the ones that come to me off the top of my head.