roger_rowlett1

I think you will want more working distance outdoors than you will get with a 60 mm micro lens. I have an 85 DX and it is the shortest lens I would use for nature macro. A 2 element achromat on a tele lens is a good alternative and make a great field macro when you don't want to carry another lens. Marumi sells them in all filter sizes. A 3 diopter lens will get you about 1X at 200 mm and about 1.4X at 300 mm. (In practice a little less at close focus). It's not as good as a macro lens but still very good. Working distance is phenomenal, 1-2 feet depending on focal length.

I've been with DX since the beginning, a D100. You would not be disappointed with aD7100 of D7200. You will be shocked at the 24 Mpixel resolution and the high ISO capability. No need to move to FX unless there is a reason to. DX has some advantage with tele work, FX with low light and wide angle work. Both DX and FX make great images. Your 18-200 will be OK on a D7xxx. The 18-140 is a little better but not much in that focal length range. Add a 70-300 VR and you have a dynamite lightweight kit. Throw in a 12-24 or 10-24 for a really complete kit.