I was very pleased with the D7000, ...I have not really kept up with features, tradeoffs, etc on Nikon bodies....
Just to be clear, you can do well with a D7100/D7200, but you might be tempted by something more, .. aaaah temptation.
Honestly Nikon impressed me with the latest releases:
D810: Seems like the top for your kind of use, but it is a high budget and thus you should take quite some pictures to justify it. + you need to master it
D750: The allrounder with the low light AF. I honestly was very attracted to it, I believe a very nice step up from the D7000, but also not that much that you would see it immediatly with the day to day pictures.
D5500: I would not go down from the D7X00 series, but it is difficult to deny that the sensor outperforms the D7000 in almost all domains.
D7200: Already revolutionising high ISO for DX and good for the more advanced use.
D5: Yes it is usable as a normal camera, but I would say you really would be looking at reliability, high ISO and need to get fast subjects, it is hard to justify for not pros (btw still on my agenda second hand in 2018 for birds in flight in the woods).
D500: the mini D5? Better to justify and a surprising move from Nikon. You need to need the super AF and FPS to justify it.
They are very good cameras, better then the predecessors and getting to a level which is more and more "easy to use", direct usable jpgs SOOC, but with a lot of possibilities in RAW.
However, Nikon has been making very good cameras, e.g. the Dynamic Range of the Nikon D7000 at ISO 100 is still at the top, so the evolutions are in some domains and revolutions are rare.