i think the D3s+D7k combo makes a lot of sense..
D7k for the outdoor shooting, where you can maximize that ISO100 DR.
Low light/reception, the D3s is fine.
I'm still debating what to do, having sold my D3/700 combo a bit ago, and now sporting the D7000 for the light engagement shoots I'm doing prior to the season starting off, whether a D3s close to a D4.
But we won't know until we know, right?!
Yes, if money really isn't the factor, of course the D4 is the best camera. But unless you've got all the best glass and the money for 2 D4 bodies, money is a factor. As I said before, if you do shoot video, the D4 might be a great investment. If you don't shoot video, I don't think (based on the pictures I saw until now) that the D4 will be worth the difference from the D3s.
If I understood you right, you don't own a FX body yet. You borrow a D700 for your weddings and you seem to like it. I am pretty confident that there is more difference going from the D700 to the D3s than there will be from the D3s to the D4 (unless the production model of the D4 will produce better pictures than those we saw until now).
If you already had a FX body, then the D4 would be a good idea, and your "old" FX would become your backup body. You don't own a FX yet, that's why I suggest the idea of buying 2 bodies (D3s + D7000) instead of one D4.
@sevencrossing, yes, based on the DXOmark tests, the D700 has slightly more DR at base iso than the D3s. But the difference is really small and from 400iso and up the D3s is the clear winner. Plus, if you want great DR at base iso, the D7000 beats both hands down. The D4 will be like the D7000. It will have greater maximum DR mainly because base iso will be 100 instead of 200. If you compare the D7000 to the D90 it replaced, at 200 iso and up, the D7000 isn't much better. The huge 14ev it gets is from going down to 100 iso.
The D4 will have greater DR at 100 iso than the D3s at 200. But from 200 and up, I doubt there will be a relevant difference.
Everything at the moment, of course, is just speculation. Although I bought a D3s not long ago, I am really looking forward to the DXOmark tests of the D4.