The optimal, although pricey, solution to the heating of a two story room is radiant floor heating. Both forced air and radiant systems invariably create air movement which allows warm air to rise. Since the warmest part of the room is at ceiling level, that energy is wasted (unless you're hosting bald NBA players). With radiant floor heating, the heat is evenly distributed all over the floor. It can't rise because there's no way for cold air to get underneath it to replace it as it rises. Consequently, the floor is the warmest part of the room and the ceiling is the coolest. And since your extremities are the first thing to feel a chill (especially as you get older), your room "feels" warmer than the reading on the thermostat. We have a two story living room and radiant heating throughout the house. The previous house I built had a two story great room without radiant and that's why radiant was a must for this house. Incidentally, it saves energy in rooms with ceilings of only 9-10', too. That said, recognize that in most places, you'll still have to install forced air ducting for A/C (and may want to install a furnace to deal with radiant's lag). One final thought on high ceilings. Lighting shouldn't be a problem if done correctly. Our ceiling has cans on dimmers in a box beam ceiling. That plus accent lighting works great (see below). Bob

I’ve lived with both. I absolutely love a two story great room. Our current new build has 10’ ceilings because there was no real way to design a two story along with all the other elements in the design with the constraints we had on our lot. Even though we have just under 7 acres, we have a creek on one side of the building pad, and slope on the other. So we could not stretch out our house the way I would have liked to. But, if there was any possible way, I would have done a two story for sure (or at least 15-16 foot ceilings). Very high ceilings completely change the feel of the room and gives you the opportunity to have HUGE windows (which I love....I’m all about the windows!). And with a two story you can really have some ceiling drama with beams etc. We have not moved in yet, but already the ceiling feels low and makes the room seem much smaller. And even though we have two full walls of floor to ceiling windows, it still feels closed in to me. It’s a completely different feel (not one that I like). I do think though that a 15 - 16 foot ceiling can give you a similar feel and is also enough room for ceiling drama. I would have gone for that as well (if possible). With rugs, furniture and fabrics, you should be able to control the echo. I never noticed a problem with that. We’re in a rental now and the great room and breakfast area are two story...there is zero echo. I think a good design of the space makes a difference (which is where a talented architect comes in).

Peke unfortunately, yes. the number of record high days are increasing. here's one article. worse, the summers of 2017 and 2018 had terrible wildfire smoke, with air quality worse than Beijing -- each time for about a month. we're being told to expect "wildfire season" more often due to climate change. in spite of all that, I still think Seattle has some of the mildest weather in general. not as hot or as cold as other places, and we don't get a lot of bugs. yes, it rains for about three seasons, but it's usually a sprinkle or mist, not a downpour. also, all that rain brings SO MUCH GREEN. it's beautiful here!

Your house seems to have all hard surfaces: ideal for sound to bounce around endlessly. Are there hard floors upstairs? If your ideas for wall treatments could include fabrics with soft backing I think that would help. Also rugs or carpets upstairs, even a ceiling treatment upstairs. Here's an article on reverberation in homes https://www.acousticalsurfaces.com/soundproofing_tips/html/noisy_residential.htm