In terms of build quality, I didn't find much of a difference between the 16-85 and the 18-105. I believe the mount material (metal vs. plastic) is overrated as long as you are using consumer bodies which are so frail that you need to take great care of the package anyway.
On a sturdy pro body, the plastic mount might be the weak link indeed, but again this is not all bad, as in the event of an impact, you might prefer sacrificing your cheap lens when the alternative is damage to the body flange which a) might go unnoticed for some time, affecting focusing and picture quality and b) would be more expensive to fix than a new lens.
Imaging quality doesn't seem to justify the price difference either. My 16-85 had very soft corners at the wide end and was okayish in the rest of the zoom range. The 18-105 is very sharp for a zoom from wide to tele. The 16-85 did have nicer (slightly warmer) colour than the 18-105 though.
The 16-85 does focus faster, but both allow for manual focus override (there are very few AF-S lenses that don't offer that, notably the 18-55, 55-200 and 55-300).
So to me, the only real difference is more range at the wide end - for some, this is a huge difference, for some, less so. You'll have to see for yourself. See here for a first impression: Nikon Lens Simulator.
I'm afraid I cannot offer much in the way of comparing the 55-300 and the 70-300 (I only have the latter, which I am very happy with), even though the differences parallel the first two lenses in many respects: some range difference at the wide end, minor build quality difference, some focusing speed difference and slight imaging quality differences. One big difference: the 55-300 is a DX lens, suitable only for DX (aka APS-C) sensor cameras, while the 70-300 is an FX lens, also suited for FX or full-frame cameras like D700, D600, D800, D3, D4 etc. Also, as mentioned above, the 55-300 doesn't seem to offer manual focus override.
Are you aware of Thom Hogan's quite thorough and still enjoyable lens reviews? He has reviewed all four lenses in question:
Thom Hogan's Nikon gear reviews.