Thanks Gonk, I was hoping you would weigh in on this.
The reason I was thinking of two 20's was the fact that I have a 65" Sony RPT that in my new theater I want to put up on a riser so the center would be around 6' off the floor. In my current house I am using the studio CC on top of the tv and the center seems kind of "disjointed". I have calibrated with the AVIA disc and the trusty SPL but when watching DVD's with a lot of dialog (eg: Mona Lisa Smile - wifes choice!!)the voices seem to be coming from above the actors not from them. I have also tried to angle the CC toward the listening position this helps but still seems off. Due to the fact I have two very large dogs I can't really put the center in front of the tv (this is also the reason for the riser). So I thought two 20's on a shelf at ear level on either side of th tv as part of the entertainment unit would be a good option.
How would I use a single 60? I never thought of that.