I’m reposting this because I’m looking for Dana’s opinion. 

(I’m guessing this is a Dana question.)

I ran a Manual-J calculation for my house. I did it in the state “before I purchased the house” and after I am done with all my insulation work. I feel the models are decent, (as an aside, the only trouble I have is the house is currently quite leaky, and i dont know how to estimate what the results of future air sealing will look like).

Im in lower westchester county, ny zone 4a

For cooling loads, I see a breakdown like this (in Btuh):
Post Insulation:
17K Downstairs
9k Upstairs
~2k Basement

Pre insulation:
25k Downstairs
19k Upstairs
~2k Basement

Our living room is large ~400 sqft, with a 16ft at it’s highest point “frustrum” ceiling, and a large 32 sqft window. That room has a post-insulation load of about 10k (pre ~14k). All the remaining rooms of which there are 3 rooms downstairs and 3 rooms upstairs have loads in the 1-4k range. This is excluding closets and bathrooms and hallways. I’m ready to install a single ductless mini split for the living room.

The question becomes what the most reasonable layout for AC in the rest of the house? 

My house has 2×4 walls, and 2×10 floors.

EDIT: My current system is in wall air conditioners, most operate at EER like 8 or worse. If I turn them all on, my electricity usage is like 5KW. So I definitely want to improve on that benchmark. That doesn’t seem hard, even at EER 11 i’m beating that benchmark by about a factor of 2.