Notes from the field: (editorial remarks after the fact)
"Surfeit of oaty goodness." (probably not, actually. .75 cup/person/day you're willing to make oatmeal.)
"Extra propane" (nope, we had plenty, the first can just leaked)
"Fingerless gloves" (warm fingerless gloves. Preferably, mittens. I wore socks on my hand one night, by the Jeezum)
"Club soda" (just to be prepared. Someone asked. We probably could have brought it instead of the ten gallons of water we brought and didn't need.)
"Chairs." (No editorial comment; it's just a good idea.)
Sand Castling (maybe a bucket? We had a moustache sculpt-off anyway)
"Nooch." (someone actually had a bunch of nutritional yeast with 'em)
Cookies were well-received. TetraPak milk is bizarre but passable.
A list of what I brought for clothing and used: (three nights, though I would have made it stretch to four no problem)
5 pair underwear,
2 pair long underwear,
1 pair pants
4 pair socks
2 light coats
1 pair of shorts
1 pair mittens
Things I brought but did not use:
notepad (except for kindling once)
2 pair socks
1 pair underwear
1 pair of pants
Bringing the bike bag: unwieldy, hard to get at, hard to get into, probably didn't even need it. The biggest hassle from a getting-at-things point of view.
Bringing extra pair of pants: maybe a mistake--I'm happy in one pair of pants until the cows come home, but what if I'd been spilled on or tore them or something? (Duct tape?)
Too Much Water: we used maybe six, seven gallons for two people for three days, and brought 17.5. We maybe should have been drinking more, and didn't use too much for bathing (ahem)--but we could have saved sixty pounds worth of weight or so.
We packed well, but man, did it take a lot of bedding for semi-comfortable sleeping. The last night I wore two pairs of socks and both pairs of long underwear and three shirts and a hat to bed on an air mattress with a blanket on top then a mummy bag then three more blankets on top next to another person. Which was comfortable and thought-free once we get it set up, which really didn't take that long. Backpacking cold-weather camping would be significantly harder, since it's impracticable to bring five huge blankets with you.
Ah, the post-vacation brain dump. Hopefully I'll need to tap into this resource again at some point.
EDIT: Holy hell we were at ~2500 feet? No wonder it was so cold.