I'm up to the pre-wiring stage for my new pool-bar cum home theatre, and am wondering whether running a few extra wires to support a 7.2.4 or 9.2.4 Dolby Atmos system would be worthwhile.

The floor in the room (6M x 10.5M) is all tiles, so i'm concerned that ceiling mounted speakers would create all sorts of reflections, and just make the end result a mess. Has anyone ever installed ceiling speakers firing towards a highly reflective floor before?

Also, my mains and surrounds are all wall-mounted at around head height, so I'm wondering whether adding additional height speakers in the ceiling would actually achieve the intended effect?

You'll be fine. Many guys here use in ceiling speakers. At least run the cables for now. Make your mind up later if you choose.

The thing with Atmos is you can really surround yourself in sound. With such a large room it would be far better then 7.1 or smilar.

http://www.adigitalife.com/audio-visual-news/dolby-atmos-128-channels-of-audio-.html

I would lay the cables now, even if you do not plan to use them immediately

Much easier to do in the initial stages

Make sure you label both ends clearly to avoid confusion later D

All done now guys, pre-wired for 9.2.6, just in case it ever goes that far