If you are installing AC and live in a green grass climatic, generally there is enough days a year where you need dehumidification but not cooling. there is a decent amount of the season and with new construction you are very tight with really good insulation so you need to actively manage humidity without cooling.
Now that you are really tight you need fresh air ventilation and you want to be able to control the humidity of that fresh air. Doing a lot of cooking for a gathering get extra fresh air and take all the moisture out you added. For the cost of installation I think it with it for any new tightly constructed well insulated house.
As for the attics. Again you could build a basement and run ductwork there but if you are going two stories ductwork and equipment is easier access in the attic. If you put and hvac stuff up there it should be encapsulated.
How much of this has direct applications to central AK I’m not sure but if you are adding AC I think there is enough crossover that these ideas/concepts need to at least be thought about.
There is more than one way to skin an eggplant. Dehumidifiers and AC work via the same principle. I reckon that my next ASHP will have a dehumidify setting like many minisplits already do. In that case I don't see a point in having a separate piece of equipment to break. Disclosure: to cope with the poor dehumidification of my low-tech AC I DO run a portable dehumidifier in my conditioned space during those wet 100% RH days in September that cruise at 70°F for weeks sometimes.
I put HVAC and ducts in my attic, and figured it was more efficient to insulate the ductwork (bc the area was smaller). This allows the roof sheathing to still dry to the interior, which seems like a good idea to me.
I also calculated the heat flow through an airsealed R-40 attic floor, and the heat leak out my R-20/R-8 trunks/ducts, and realized is was low single digits on my total energy loss.