I think some pretty good guidance has been given here.
However, there are some good ceiling speakers out there... in this case, there is a good option for wall-mounting small cabinets, but in some cases, it's just not practical. In that case, a good ceiling speaker (especially one with an aimable tweeter) can do wonders. I've used some of the higher-end Boston and Tannoy units for this purpose... they did very well. Truthfully... if you get the surround speaker in a good location, relative to the listeners (above and behind), as long as you don't just use junk back there, and it timbre-matches the fronts decently well, you should be able to make it work quite well...
In essence... don't throw out the idea of ceiling-mount, if it saves you from worse options...
Regards,
Gordon.