The space issue is a good point, and I had not even thought of it until you brought it up. I too had the same problem, the simple fact is the CC-690 is monsterous. It looks like a Studio 60 turned on its side.
At first I didn't plug it in, but finally I figured I'd set the tv on top of it with a thin textured mat to seperate the two. Best solution I could come up with without buying a plasma/lcd TV to mount on the wall.
I don't know your circumstances however, but I would agree with Highbar and Mazer on this for sure, go with a single Studio 20 if you can, it will match performance-wise the Studio 60's, and it is smalled then CC-590/690 option. Its just a little more akward to place I think thats all.
I doubt the CC-190/290/390 will match well with the Studio's either. Different components and build quality all around.
What type of system are you running currently? Are you more interested in the HT setup then Stereo? What are the limitations you have in this room thats creating problems?
If you still don't have surrounds right now, and have no intention of buying them then I would forgo the centre channel completely, especially if you have room constraints.
If however you are planning on running a full 5.1, or 7.1 setup, and its just the room cramping your style then I'd look for ways to make the space. Sacrificing a matching centre channel in a surround sound HT setup based on room constraints is what I see as the least desirable situation. A poorly matched centre will have you going batty because you will always be picking up audible artifacts that don't belong or match.