Due to constraints in my family room I have my front speakers mounted high up near the ceiling aimed down. The tweeters are pointed at the seating area so they meet that requirement. I don't have any way to add height speakers therefore (unless they go IN the ceiling forward of the mains, but it's a flat roof with no room under the drywall of the ceiling).

My main right and left speakers are home brew, and taking an idea from an NHT design they are angled at about 20 degrees (the baffle board is tilted not the box). I also put the WOOFER on top of the tweeter with the idea that it would be mounted near the ceiling.