Three lens combination. 14-24mm f2.8, 24-70mm f2.8, and 70-200mm f2.8. The combination will cost more than your D3 but all three lenses are 2.8 and have excellent image quality, unlike the 18-200mm DX lens which is a do everything with mediocre image quality in comparison. Thom Hogan has reviews of most of the Nikon lenses and suggested combinations.
http://www.bythom.com/nikonlens.htm

You should spend some time on his site reading the reviews.

Thanks for the site, I have never heard of it before and a cursory glance shows an amazing amount of information.

I currently own a 17-35 2.8, a 35-70 2.8 and the 70-200 2.8.

I was thinking of replacing the 35-70 with the newer 24-70 2.8.

What I am looking for is a single lens to bum around with. I was just curious to see if there was a lens like the 18-200 in the 2.8 range for FX cameras.

There isn't. And there isn't a single lens solution for DX in 2.8 either. It would probably weigh about 20 pounds and cost $15,000 if there were.

How about the 20mm F4 and 75-150mm series E. That will give you a small and light two lens solution that both take 52mm filters. I picked up both recently for under $200 each.

Realize that the 18-200mm works in DX mode on the D3, and gives somewhere around 5MP resolution. Considering the quality of the D3 pixels, 5MP is high enough resolution to make some pretty formidable prints. As a bum-around lens, the 18-200mm is superb. I don't bring it into a critical shoot, but when just hauling the camera along with nothing specific in mind, it is a great image grabber.

I get the feeling that quality varies from lens to lens, and I got lucky. At f/11 or thereabouts, it is really more than just "acceptably" sharp. With my typical ambient light people shots, no one has ever complained about lack of sharpness.

Others have reported significant vignetting, but I have to shoot an evenly lighted gray card just to see any. Invisible in a normal photo. Often camera movement is mistaken for poor focus or lack of lens sharpness, and in this case VR works very well - though it has limits. Of course it does nothing for subject movement.

I do have the gold-ring 12-24mm and a nice arsenal of primes that are stunningly sharp. However, there are times when having a "walkin'-'round 'n' shootin'-stuff" lens is the order of the day, and the 18-200mm does this exceptionally well.