I've got a similar setup and went with a C2 for center, CM5s for rears and DS3s for sides. While the C2 is a nice speaker, if I had to do it again, I'd get a single CM9 and use that as a center. Maybe its mental, but I feel like I'm missing something from my center channel.
The CM5 is a bona fide bookshelf speaker and is probably overkill for rears, but I had them so I used them. If you want to save some $$, go with the CM1. The DS3 is OK in monopole mode, but really falls off in quality in dipole mode. I went with them anyway because I had limited space on the sides and needed a speaker that didn't protrude into the room as much.