Now that I have bought this Nikon 28-200mm, I now have four mid range zooms. Each have their pluses and minuses, as follows:
1) Nikon 24-85mm f2.8-4D - This lens is sharp and relatively fast, but it is also quite heavy. Sometimes I wish for a bit more telephoto. The 1:2 macro function works very well.
2) Tamron 24-135mm f3.5-5.6D - This is a good overall lens. The balance of wide and telephoto is really nice, and optical performance is very good for the zoom range. The biggest problem is weight, and it feels heavy on the D600.
3) Nikon 28-105mm f3.5-4.5D - A nicely weighted zoom that performs reasonably well optically. It feels well made and performs well, but doesn't do any thing spectacular. The 1:2 macro feature is a real bonus. I've had this lens about 10 years now, and I got it with my F100 as a kit zoom. I used it extensively for about 5 years with the D100 before I got an 18-135mm DX zoom, but I have hardly used it since then.
4) Nikon 28-200mm f3.5-5.6G - I've only just got it, but I think it will be a handy lens. Versatile and sharp, but with lots of light fall off at 28mm wide open.
Really, I have too many lenses in this range, so I really have to cut down to a couple lenses. It remains to be seen which ones I choose to keep.