Spaceman- you bring up some valid points.
The living room is going to be remodeled anyway, so if I don't do the theater there, I'll be doing the living room AND the basement, which will add considerable cost and time to finish. I also like the convenience of having the theater on the main floor for when I have guests over for a viewing party.
As for the air conditioning-- My central air unit went out in 2010, and the house lacks adequate ductwork to the second floor, which is something I was going to address with this project. I am planning to have a geothermal system installed this summer, and once I upgrade the ductwork that will provide adequate cooling. Most of the time I will only have 2-4 people in the room at once.
I forgot to mention earlier that I also ordered a 100" 16:9 FAVI electric screen. I debated between Accuscreen, Elite, FAVI and Focupix but couldn't find any definitive answers as to which one was the best in the price range. The reviews I found were all pretty good, and I feel I got the best deal at the time, paying $168 w/free shipping and no tax, plus getting 13% in rewards from the retailer and 1% cashback from my credit card.
I'll rework the living room sketch when I have time (not sure which program is best for floorplans) and work on one for the basement as well. I have to get the pictures of the basement uploaded and find my measurements. I've only got the Length, Width and Height for the basement, not the location or size of the pool table or doorway location. More details on the basement may have to wait until I'm home again in mid-May.
One thing I'm considering with the basement to keep the floorplan open and increase viewing distance is to hang the screen close to the south end of the pool table, then have my back row of seats against the south wall, which would allow me to have the full row of 4 (on a riser), with the row of 3 in front of those. The problem I have with that layout is speaker placement for the front and center speakers.
Here is one picture of the basement, taken from the North end: