re: tweeter height, it depends on how tall you are and how high your chair/sofa is. I always mount my speakers higher than recommended, then again my ears are mounted higher than normal as well (I'm ~6'5) so it all works out.
If by "real" world you mean situations where the speakers can be mounted in exactly the way the manufacturers recommend, yes they exist but they are normally purpose-built while finishing the basement. If you think home theaters are exotic you should see the lengths people go to in order to make the perfect stereo listening room :
http://forum.audiogon.com/cgi-bin/fr.pl?vstrt&1098913241 
