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I'd take the D800 without the grip. With all due respect to Kent, I wouldn't take a backup unless it was a P&S - that is a lot to carry if you aren't a working pro.
As for the lenses, I really loved my 35 1.8 on my crop-sensor on my recent trip to Japan. There were a lot of opportunities to get creative with composition and DOF, and I found myself shooting with it quite a bit.
I'd take the 24-70 for a walk-around lens. It is a big piece of kit, but obviously a great lens. (I have a Tamron 28-75 f/2.8 that is my go-to lens)
For the long zoom, I'd go 70-300 over the 70-200 Siggy for the weight and reach. For the way I shoot, I didn't need the fast glass as much as I needed reach. I took my 80-200 f/2.8 ED on my trip to Japan/China, but the weight was so much that it stayed in the room in favor of my 18-200 VRII.
Those three lenses with an ungripped body is manageable for bulk and weight, but isn't exactly traveling light. In a pinch, I'd probably go with my 18-200 and 35 1.8 as a light kit. A lot of folks sneer at the Nikon 18-200/28-300/18-300 lenses, but I love mine for travel.
Are you taking a tripod/monopod?