Third Party lens for Nikon D 800E
First, congratulations. I hate you.
My petty jealousies aside, everything mentioned here so far are worthy lenses.
I think it boils down to the obvious - budget and style. I'll take a guess that you are perhaps looking at 3rd party to save a bit of coin as opposed to wanting an alternate to the excellent Nikkor WA lenses.
Personally, at least for my style and use I'd be looking at a zoom with AF. The Sigma 12-24 is an excellent piece of kit for not a whole lot of money. The distortion is low(ish), it's fast and sharp. And incredibly wide. In fact - as I'm contemplating my own move to FF, that's one lens I'm looking at - and budget is not really an issue there. It's truly a UWA lens.
Here it is tested on a Canon at Photozone:
The Tokina 16-28 is also a very interesting looking alternative to the Nikkor lens - also with the bulb type front element. It's pretty new(ish), but looks to be built like a tank - and is fast. I like the fixed aperture - and it's still plenty wide for most purposes.
Good luck, and have fun!