I struggled with which lens to pair with the 24-120. The 70-200 f/4 is a good choice but with some obvious overlap in both focal length and aperture. However, sometimes some overlap is a good thing, so having two very nice f/4 zooms to cover 24-200 makes sense.
I tried the Tamron 70-300 VC to extend the range, but then decided for my type of shooting (mainly portraits) the Tamron 70-200 f/2.8 VC would be the best choice for me. This lens is in the same price range as the Nikon f/4 zoom, but with an extra stop (and a bit of extra weight if that is concern). Prior to owning a Nikon system, I used a 70-200 f/2.8 IS II for a while, and I can honestly say the Tamron is right up there with it in AF speed, accuracy and IQ.