I'm having a house built which has 10 feet ceilings in the living
room. I'm debating where to put the surround speakers. One side of
the room is all sliding glass doors, thus ruling out the possibility
of putting a speaker on the wall at ear-height.

Therefore I need to put them either in the ceiling, or close to the
ceiling (between 8 and 10' up). If wall mounted, I could angle them
down to point at the couch, but the room is 20' wide and hence the
speakers are going to be a long way from the audience.

I'm thinking I may to better to get in-ceiling speakers and move them
in from the side walls. Anyone have any practical experience or
opinions on this topic, or know of a good source to help me resolve
this.