D4 & D7000 or D3s(used) & D800

I shoot weddings so I know that I need a backup camera.

Right now I have the D4 and D7000. I love the D4 but I also know that I don't use a lot of the features and the difference between it and the D3s is small.

I'm throwing around the idea of selling the D4 & getting a used D3s instead. With the trade I could upgrade my D7000, which hardly gets touched as it is now, and get a D800.

I'm torn on the D800 and weddings. I don't feel that I need 36mp and the file sizes are somewhat scary for me and my workflow...but it seems like the D800 could add a different option and a backup that I would actually use.

So, am I crazy? Which pairing would you rather have for weddings/portraits? Are skin tones on the D4 better than on the D3s?

Those are my questions...I'd love your feedback on this dilemma.