The D750 and the D7100 make a good combination. As for getting the D7200, that's a judgement call. You can sell the D7100 on ebay. Try some comparisons.

Read comparisons and specs, and decide what features are important to you.
(Reviews) https://www.youtube.com/user/TheCameraStoreTV/videos
http://cameras.reviewed.com/
http://camerasize.com/
http://www.imaging-resource.com/IMCOMP/COMPS01.HTM
http://snapsort.com/compare
http://www.dpreview.com/products/compare/cameras?utm_campaign=internal-link&utm_source=mainmenu&utm_medium=text&ref=mainmenu

Here's what the D7100 has sold for lately.

http://www.ebay.com/sch/i.html?_from=R40&_sacat=0&_nkw=d7100&LH_Complete=1&LH_Sold=1&rt=nc&_trksid=p2045573.m1684

I know, we stay in the same town and know almost everyone there. When word gets out that we are coming, the Amies are coming, people start to plan when and where we will be eating and the food is great! We too have had visits from the friends we have made over there. One lady that I met has really gone deep into Photography and even gone to a formal Photography school for a year and a half and is about to change her career. I like the weather better in September and October then during Karneval and every other year is Photokina. I stopped the wedding thing years ago and will never again do another one again unless it's in either England or Germany. LOL When I did carry more gear I too would only take what I needed for our day trips that sometimes turned into 2 or 3 days. This year was the first time I ever traveled so light and you know I got all the shots without any problems.

I travel to Germany for a month at a time. In September I took my Canon 7DMKII with a kit lens (18-135) and it covered everything just fine. I like to also take a tripod for night shots but as I was carrying two large canvas prints rolled up in a tube I bought a small Manfrotto tripod in Germany for just under $100.00. I have traveled to Germany and England with a lot more gear, when I had weddings to shoot and it was a hassle. I don't shoot BIF or wildlife over there except for the wildlife that's up close during Ocktober Fest. It was so much more enjoyable this last trip traveling so light, I felt like a tourist but it was in the back of my mind, I don't have any back ups. Take lots of memory cards along with extra batteries and a cable release. I didn't want to stand out in the crowd and I sure didn't want to keep watch on a camera bag while I was shooting. What ever you do, have fun, shoot a lot and drink a beer for me.