Great match. I prefer this lens to the Nikon equivalent for its smaller size to be honest.
You're right, the Sigma is much smaller and lighter. But I'm not sure I would take it over Nikon's, their 24-70 is one of the greatest general purpose lenses ever made in my opinion. And I say this as a Canon fanboy.
Nikyd, as long as you don't want to do significantly wide-angle work, it will be a great match for your walk around and especially people shots with the 2.8 aperture. It may not compare to Nikon's gold-ringed work of art but it's still a very good lens. Can't beat it for the price if you ask me!