A lot of the advice here is good.
My room is about the same size as yours. I've had Altec Valencias and Santiagos over the years. The Santiago worked slightly better due to the sealed box design
Long wall placement never really worked . Not enough distance to get them to integrate properly . I'm guessing Klipschorns might be the same problem.
I currently run Altec 14s and found the smaller 12" bass/ mid driver seems easier to control vs. the 15" of the other models.
I do run a sub as the 14 roll off quickly around 60hz.