I have the 5D MkII and the main bug bear is the fall off in resolution on some lenses towards the edges, and particularly at the corners. The focal length equivalent is sometimes an issue especially with macro where filling the fame needs more magnification.
On the other hand I would say that the build quality is better than the 7D, but I think they are very different animals.
I'm not sure why the pixel count at these numbers is important to you, the 5D MkII will easily print at A2 native the 7D isn't far behind how often will you printing off at A1 because both cameras will easily upscale to that, in fact 10 MP is usually more than enough even for large prints. The real benefit comes in cropping, but do you do a lot of heavy cropping?
The original 5D had 12MP and I don't recall anyone thinking that it wasn't enough for wedding photography.
I'd like to mention a new kid on the block which you should consider, and that's the 1D MkIV, a 1.3x crop with 16MP. There's a comparison between it and the other two cameras
here.
Of course it costs a lot of money, but given the pro quality and the image quality it might be a long time before you need to consider buying a replacement (but I'm sure I remember thinking that before!)