The D3000 is an excellent camera, but the D5200 has a better sensor (not MP, but image quality) and better autofocusing. It sounds like both would be useful in the photography you enjoy.

Sensor quality, in particular, had been improving rapidly around the time the D3000 came out, but it has slowed down the past year or two, so the D5200 should be "competitive" longer than the D3000 was.

There are a lot of options out there, so it's not an easy decision. Since you sound like you want a DSLR, the simplest suggestion is to get an entry level body with a "normal" zoom kit lens. That will give you a lot of power, control, and quality.

Two specific suggestions are the Nikon D3200 with the 18-55 lens ($500) or the Canon EOS Rebel SL1 with the 18-55 lens ($650). Both brands and lines of cameras should be around for the long haul (10-20 years), it's not easy to say the same with confidence about a number of the other options.

I think, compared to your Kodak P&S, your lighthouse picture will be much more vibrant with either of these options. And, if you continue to enjoy the hobby, you can add lenses or upgrade the body over time.

Since you're upgrading from the D60, and staying with Nikon, the biggest question is which one: D3x00, D5x00, D7x00. They are all excellent, the main question is how much control you get and how easily you can change things. If you haven't really been limited by the D60, then the D5200 is the right fight. If you often think, I wish I could do X, then look at the D7000.

I helped a friend buy a D5200 earlier this year, she's been very happy with it. She even shot a friend's wedding with it, with no regrets.

The two biggest differences: the sensor area is 13x larger in the D5200, and the lenses combination will be optically better, since the lenses only need a 3x and 5x zoom range, so the optical engineers aren't making as many trade-offs.

What sort of shutter speed/ISO were you using for the pictures which seemed acceptable?

Your camera is fine. It's more than fine. The only significantly better cameras you'll find for what you're doing is the Nikon D3s (> $4000 used) or D4 ($6000).

While shutter speed seems like the most important decision, it really isn't. Aperture is your physical limitation, so I'd use A mode, and shoot at either f/1.4 or f/2. Set the ISO where you are happiest (probably 1600 +/- 1 stop). Then, once you know the shutter speed you are getting in the poor light, take shots of the action which suits that. Dancing is not uniformly moving, there are times when the dancers are moving faster and slower. Use your knowledge of the activity to make your pictures better. The monopod can help, you'll be able to pan a little and avoid adding handholding vibration.

Using the faster lens is better than VR for this. Also, the faster lens will allow the AF sensor to work better, since it will have more of the limited light to operate.

You also want to be careful about the AF and "drive servo" settings you use. The 3D tracking on the D7000 is excellent, you probably want to take advantage of that, but make sure the focus sensor stays on the dancers, it can easily switch to the background. The continuous high mode does not focus during the sequence, so only continuous low or single shot modes are good to keep focus.

When comparing two lenses or two sensor sizes, magnification and field of view are the same thing.

Pair the 70-300 with the 18-55 for a great combination.

I agree, the 70-300 is an excellent option. Personally, I don't like using lenses with greater than a 5x zoom range, so 18-105 would be just outside my preference. A 17x zoom range just seems too optically challenging.

I wouldn't worry about the crop factor of the D7100, you can do the same thing in an editor. The only thing that the in-camera crop factor does is give you smaller files when you shoot.

The 50mm f/1.4 would not really meet the need, especially with a crop factor of 1.6x, making it a 80mm f/1.4.

If you really want a new toy, the Canon EF-S 10-22mm f/3.5-4.5 USM is the way to go (about $600 online). On your body it's a 16-35 lens, and it's a perfect complement to your 24-70.

If you want fast glass, add the 50mm f/1.8, it's cheaper generally as good as the 50mm f/1.4. Hard to go wrong with such a good $120 lens.

There are many comments about "file size". If you're comparing the D800 with the D700, the file size triples, and you might notice if load time goes from 3 sec to 10, for example. Bu t the D610 is 24mp, so the file size difference is less significant. In the same way, 24mp vs 36mp doesn't really affect cropping or sharpness.

In the end, we're talking about some spectacular cameras (D300/D300s, D7000/D7100, D700, D600/D610, D800/D800E). If you have one and do not feel limited, keep enjoying it. If you do feel limited, is it the body or the lenses? Especially for sports/action, faster lenses are really important, because the AF sensor will get more light and be able to operate faster. (NAS is very common, but there are several solutions!)

The D600/D610 have the nice feature of U1/U2, which are better than the custom function banks of the D800. The D800 seems to have better AF sensor coverage. Other than that, flip a quarter. Or 4000 quarters.

I shoot a lot of volleyball (indoor and outdoor), and single shot seems much more effective than continuous, so the frame rate doesn't matter. When you know the sport you're shooting, you know when the key shot happens.

If response speed is really important to you, I think the D3s is king of sports.