Height Speakers A Home Theater

I am considering getting the new Onkyo or Integra 9.2 pre-pro with the front height channel feature. I looked at the online manual for each unit and it does not have a recommendation for how high or wide the height channels should be. Anyone here using height channels?

These pre-pros have the front wide channel feature also. Heights, fronts, center and front wides...yikes! That's seven speakers in the front! Has anyone here tried this before?

My ceiling is 22 feet high. The link to my room is below.

Click Here To See My Room

...thanks for your help,

I have the Onkyo 5508 on a 7.2 set up. While I am not using the 2 additional front channels, the processor will automatically calibrate the output of the speakers depending on the distance between the speaker and the listener as well as your component specifications. From there, you can manually adjust the sound levels to suit your taste.