Your old Klipsch are a rather large array of drivers. It takes a minimum amount of distance for the output of the array to blend into a cohesive front. Your room's dimensions have you fighting against this. As far as Klipsch and your room go, I think the KL-650 THX would have been a more sensible choice for your mains originally. (If you decide to stick with Klipsch and are willing to go away from a tower, those are really rather good speakers worth considering.)
If you really want to do this right, get Floyd Toole's book on acoustics, study it, and get ears on an assortment of different speakers to put Toole's info into context. While speakers may be gorgeous furniture and nifty toys, they are fundamentally tools for music reproduction and should be chosen accordingly, as determined by the room and the user's particular demands.