Scott E.:

So in this scenario, where would the best place be to put your left and right speakers?  Is there a ratio for distance from rear to side walls?

Yes. Generally the rule of thirds is a great place to start if you have the flexibility with placement options; try putting your tweeters at the 1/3 points along both width/length axis. if one/both of those points are not feasible, try 1/5, then 1/7, etc. But generally 1/5 is good for most folks. There's not necessarily a rear/side ratio, but if making sure your tweeters are not equidistant from both rear/side walls is also a great place to start.

Hope this helps!

- Oliver