@madog2diver - The D7100 is also completely usable in completely no-brainer P&S mode if you want or need that. At the same time, you can get it to do almost anything you want. I say take the $400 and go crazy. Of course, you might not ever let your wife touch it! (My wife owns a D3100 but also borrows mine.)

I have done some teen-league sports shooting and birds-in-flight action shots with the D7100 with no problems, but I do not (normally) shoot raw unless I am on assignment, so the buffer is large enough.

The D7100 is a truly versatile DX-format camera. It will do anything you want it to do with great ease of use. It may not be ideal for sports/action shooting because of buffering limitations already mentioned, but with the right lens, it can manage well enough.

I have no complaints about my 7100, which gets a workout as both a field and a lab camera as well as serving me on freelance journalism gigs. I can't imagine what upgrades Nikon might have in mind for a new 7200.

I'll second the vote for the D7100. The real question is why you would want to go full-frame. If you can make a compelling case based on your real shooting needs, okay, but it will mean heavier and more expensive glass forever.

For serious amateur or semipro shooting, the D7100 is a great camera. None of this hunting through menus to change settings. Shooting mode and drive are both locked knobs like on classic film cameras, everything else you would normally need--iso, white balance, exposure comp, etc.--is a push of a distinct button away. With the top-of-camera LCD display, it's a cinch to make quick changes to accommodate changing shooting requirements.

Try one at a camera store and compare to your other choices.

I'm completely happy with my new Tamron 16-300, the most versatile walk-around lens you can get. I do general photography and freelance journalism with it on my Nikon D7100. The only time it has come off in recent months is when I do portrait work or serious specimen macros for my scientist wife. Then the beautiful Tamron F2.0 60mm macro goes on.

Another thing to factor in between DX and FX format is size and weight, not just of the camera but also the lenses. The difference is surprisingly big. My wife, who shoots for her work as a naturalist, sticks with her D3100 precisely because it fits much better in her smaller hands. For my part, I do not expect ever to move up to full-frame, as the D7100 is as big and heavy as I want to go.

The "real pro" photographers I sometimes end up hanging out with covering events mostly shoot full-frame. Some of them change in how they deal with me once they see my equipment, but I still get published in newspapers and photo mags. So, who's counting millimeters and pixels?

From the D3100 you have a couple of upgrade paths. A modest upgrade that still preserves the compact physical size but adds quality and versatility would be the D5300. I used a D5100 for years, really liked the articulated screen (shooting crowds and celebs with camera held over head is a cinch) but did not like the clumsy menus and shortage of physical controls.

I'll second the recommendation of the D7100. That's what I am now using as my main camera. It's bigger and heavier, but if you are at all serious about photography, it's worth it. Every shooting setting you need is just a dial or a button-wheel away. With the top-mounted LCD display, you can quickly set ISO, white-balance, compensation, focus-mode, metering,... without turning on the screen or putting the camera to your eye. And it is the least expensive of the D-series with weather sealing.

Do some comparisons and read the reviews at dpreview.com, but I would really recommend the D7100.

On the D7100, Auto distortion control under the shooting menu is available only with type G and D lenses, according to the manual. It should be available through the retouch manual if you really need it, although the kit lens may not have enough distorion at its limits to justify having created a profile.

I do some freelance journalism and event photography where lots can be going on and shot opportunities come and go very quickly. Shooting with both eyes open can help keep you from missing important action. The downside I find is that critical composition can suffer with my attention divided between what is in the finder and in the world. Under those circumstances, I always try to frame generously so I can crop later.

Shooting at other than roughly "normal" focal lengths (~45-55mm equiv.) can also be disconcerting and presents special challenges. On the other hand, both eyes open can be almost a requirement when trying to track a fast moving subject with a 450mm telephoto. If you lose the hawk in the viewfinder you'll never reacquire him without opening the other eye.

I also used the Nikon 18-200 lens for years, but between the zoom creep and the lack of weather sealing, it was time to move on.

Enjoy your new lens!

The differences between the Tamron 18-270 and the 16-300 are numerous: more than 10% more on wide angle and on telephoto end, weather seals, better ergonomics, improved VC, closer focus, etc. The 18-270 is being discounted for a reason.

Any of the three super-zoom lenses you were considering will do the job for what you want with acceptable results. You may have to just decide on secondary features. I do a fair amount of field work for my wife (a teacher-naturalist and marine biologist). The weather seals and excellent built-in close focusing of the Tamron is a real plus for me.

I have used the Nikon 18-200 VR for years as my walk-around lens on a D70, then D5100. I hated the zoom creep. After upgrading to a D7100 body, I purchased the new Tamron 16-300 when it first was released and love it. It is as good as the Nikon with many small advantages (a little smaller, a little lighter, no creep, weather-sealed...). Look for my review over at dpreview.

http://www.dpreview.com/forums/thread/3674229

No super zoom lens is going to be super sharp, but the Tamron is acceptable with great range. And the price is right for the amateur or semi-pro.

At full crop (see photo, this looks reasonably sharp center frame. Some purple fringing evident on edge of chimney. The results are not absolutely razor sharp, but you will not find that in any all-in-one super zoom. (I went with the new Tamron 16-300 for my D7100 and am happy with it for what it is.)

Center image, full crop

For the record, I am a part-time journalist/photo-journalist, so my involvement is semi-pro. I picked up the Tamron 16-300 as a universal walk-around lens for my all-Nikon stable of cameras (latest: D7100). I posted two early reviews at dpreview. The more thorough one with test shots is at:

http://www.dpreview.com/forums/post/53716819

As to IQ, the lens is noticeably soft at the long end, with some small vignetting. The biggest weakness is optical distortion which is endemic to super zooms in this class. For my purposes, this is rarely going to be a problem and the pros outweigh the cons. I really like the lens, which is better in every particular to the Nikon 18-200 it replaces. But see the full review and test shots at the link above and judge for yourself.