Is your home layout so you could use 20" floor type fans to move air through the kitchen & back to the A/C?

I cool 3 rooms & a hallway, nearly 900sf, (with only "one unit") a mere Half-Ton 6,000-Btu/hr window unit located in the living room, with the air first circulating through the dining room, then through the kitchen & back to the units Return Air intake.

I use (2) two 20" Wind Machine 3300 fans purchased at Wal Mart; those fans are terrific & have vertical adjustments.

Read how I do it, & view my 1937 home that I cool perfectly, even at 104-Heat Index. - udarrell

I need to cool three rooms a length of 44 ft. The living room in the center does not have suitable windows. There is a small bedroom at one end and when the door is open a fan could move air conditioning in or out. At the other end is the dining room with a window facing the living room and a window facing the kitchen. I could put a fan in the dining room but no room for a return fan in kitchen area.

I have been thinking of an air conditioner in both the dining room and the guest room. But perhaps I should try just the dining room (and the one that is going in the master bedroom) for now. Does it make a difference which dining room window I use for the most efficient cooling or adjoining areas.

"These are only suggestions, I am NOT telling you what to do, use only your judgment, NOT mine."

I would try the small bedroom window unit in the dining room with the fans & see if it can handle the cooling okay. Then you will know NOT to get one over 8,000-Btu/hr.

For efficiency, you want long run-times NOT short-cycling!
Let me know how things go!

I am a long time (started in mid 1970's) retired HVAC Contractor & Tech - udarrell

There are a multitude of things that have to be done correctly, or you will have problems even with a brand new central system.

I have fuel oil heat & it is costing me a fortune to heat my home. My actual electric bills, "in an all electric home, during the cooling season," usually stay within $45.00 a month all summer. We have some hot & humid weather here during July & August, up to 104-F Heat Index.

Also, the government is talking about raising the minimum A/C SEER levels. For many reasons, I am totally against that.
Some of my reasons are on the linked pages. - udarrell

we have an OLD 5800BTU unit that cools circles around every newer 6-6200BTU unit we can find. the difference, the old unit moves 3x teh volume of air, thus cooler quicker and better.

efficiency don't mean a thing IF they run forever and never cool it down. then you only waste electric. don't get me wrong, you want it to run long enough to remove humidity. but i am just not a fan of the newer models at all.

our tower sites have fixed equipment that always use the same amount of electricity a month. the above mentioned 5800 btu unit kept teh small(6x8) building cool as we wanted, even with outdoor temps over 100. the 6000 and later the 6200 we installed in the same building never could cool if outdoor temps were above 80, and they ran continuous. the electric bill showed a 40% INCREASE during teh times they were installed compared to teh same months of use during the times teh 5800 was in. we actually spent 100.00 for a new fan and put the 5800 back in, it was cheaper to pay more to fix than to pay less to replace but have bigger energy bills. and for your reference, the bills vary by only $10.00-$15.00 over a 15 year span OTHER than the 6 months those new "efficient" models were in, and those months were as much as 80.00 more!

so, as long as you don't have a high heat load and don't mind leaving them on even when you are gone for a while, go for it.

I believe in using fairly small units (around 6,000 BTU and using several). I have four of them, total of 2 tons cooling capacity, and my house will stay in the low 70s when it's humid and in the 90s outside. I am not a big advocate of fans along with a/c. To me, fans are noisy, and their motors add some heat, plus use some power, but I realize that some houses may need them to distribute the cool air. But that's why I like the 6,000 BTU units - you put the cooling right where you need it, no need to move a lot of air around with a bunch of fans.

On the issue Davidandkasie brings up about the different units and their efficiency ratings, old vs. new ones, etc., here's what I've found: The new high-EER units use more airflow to keep the evaporator warmer and remove more sensible heat (degrees measurable on a thermometer), and less humidity (latent heat). So in terms of measurable efficiency, the new ones are probably a little better, but since they cause higher indoor humidity, you probably wind up cooling to a somewhat lower temperature to be comfortable, so it's a wash. But it does not make much difference as a practical matter because the units you're going to be buying today will be the higher-efficiency design.