I have both the D5100 and the D3200. Until the D5200 comes out, I need both of them. I originally bought the D5100 because of it's articulating screen and it's high resolution. I like shooting photos of my model trains, which sit on the floor, and are otherwise very difficult to photograph without that screen and LiveView. Here's one example. Shot with the AFS 35mm f1.8 DX lens.
Here's another use for the D5100. This time the camera was over my head. The Hummel figures are on the top of my bookshelf. This one was shot with the kit AFS 18-55mm DX VR lens. Neither photo was sharpened in post.
I bought the D3200 because of it's high resolution. I enjoy measuring the resolution of all my lenses. The D3200 resolves my charts with much more clarity than any other camera I own including the D5100.
Both cameras perform flawlessly. I have not found any shortcomings in the AF systems or anything else. I'm even using both bodies with my pro lenses and even my manual focus lenses in manual mode. The D3200 has become my top DX body for use with my long lenses as well as my ultra wides.
I might get the D5200 after it comes out and give my D5100 to my grand daughter who is now a freshman in high school and has shown a great interest in photography. She's currently using the cheapest and mostly automatic p&s.
If I were you I would probably hold off for the D5200 even though your photography needs are probably a lot different than mine.