I have a balnk canvas right now and don't own the furniture and the walls are not in place yet so I have flexibilty in this regard. What is the best case senerio?
LP
In addition to Don's comments:
lengthwise setup of room.
ample space between speakers and boundaries, listener and boundaries (with the most common culprit being the back wall).
try 38% room length in rectangular room for starters. tweak from there. once settled, you can then decide on screen size for desired viewing angle.
for 5.1, 110-135 degrees, so that side+rear areas can be straddled.
if 7.1, you have more freedom in bringing sides to 90 degrees, as rear area is now covered, and you now would have a more complete wrap.
some thoughts...