1. Agree, DHing is terrible domestically and needs contractual language codifying the procedure.
2. The procedure should be guaranteed C+ or better aisle/window or we don't board. At pilot discretion, we can accept another seat for leg block above rotation or reserve guarantee.
3. That guaranteed seat needs to be automatic, no 10-step process to book my seat. I show up and with zero input and I board my DH in my preferred seat
4. I'm sure there are a few who are APU misers but my guess is most captains; at least out of self preservation, are trying to keep the planes cool. My last trip we had warm planes on every leg and there wasn't a thing I could do about it. Ran the APU non-stop, sometimes had air and sometimes didn't, but the cabins heated up to the low 80s regardless of my efforts to keep them cool. Our external cooling equipment is garbage. One station I spoke with the station manager about his cooling hose with a nice 3" hole right next to the air attachment point. Other stations get the infamous sausage hose.
Good suggestion above to remind FAs to ask the PAX to pull down the window shades, I'll add that to my brief.