D7100 - DX, 24.1Mp, 51 focus points, very good hi ISO/noise ratio, $1,196.95
We must take into account that you're primary using the camera for landscapes, portraits, and still lifes (some at night). I'm going to knock out price as a factor, although from top to bottom there is a $1,600 difference.
For me, your planned uses would knock out the D7100 for you. It has "reach" as you put it, but none of your mentioned uses require reach.
The biggest difference between the D800 and D600 is mega pixels, focus points, and something I didn't list, the feature set, but for your use, I don't think the feature set nor the focus points will be a particularly big deal. The high ISO/noise ratio gives an edge to the D800, but it's only an edge.
As to the Mp, unless you have a very old computer which would already be giving you problems with the Creative Suite 5 you currently have, I don't think you're going to particularly notice a processing speed difference in your computer with the D800 file size. You will be taking up hard drive space more quickly with its files.
Okay, I lied about not using price in the analysis. The difference between the D800 and the D600 is $800, but that wouldn't deter me from the D800. For capturing detail in landscapes, portraits, and still lifes, it's wonderful, as long as technique is up to par.
If the extra $800 doesn't mean a lot to you for the purchase, I'd go with the D800, but if it's a big factor, the D600 will work out fine for you.