Since my cathedral ceiling is the roof, and the roof joists are only 2x8's, there's not enough depth for in-ceiling speakers and insulation and air space, so I use surface mounted speakers.
I use 4i speakers for Front and Rear Tops. They work just fine, but bigger would be better. I'm actually pretty amazed at how well they work, but I cut off the bass at 120Hz so they don't need to try too hard, and the low bass is directed to my Expressions since my subs are ONLY for LFE so the bass is awsome.
I use ElectroMotion IW for the Surrounds and Rears and they a MUCH better speakers. The speaker that Robert suggested, the IC, is pretty much the same speaker in a different configuration, so they get my vote for sure.