Best Nikon DSLR cameras under $800 - or around $800?

What DSLR cameras would you recommend in that price range? And what lenses would you use for landscape shots and macro pictures?

The camera that fits your needs will be something like a refurbished Nikon D5300. The reasons are many.

The D5300, while an entry level camera, can be tethered using either Lightroom CC or the new Capture One v 9
It has an articulated LCD (which many novice photographers find to be important)
There's a built-in GPS
An intervalometer for shooting time lapse

Costing under $500, you will have enough money to purchase the Nikkor AF-S 40 mm f/2.8 macro lens.

The 18-55 mm lens that comes with the camera can be used to shoot landscapes using the lens at 18 mm.

For spectacular landscapes, you will have to save your pennies a while longer and look at either the Nikkor 10-24 mm wide angle zoom or one of the Tokina wide angle zoom lenses (About $550 vs $900 for the Nikkor lens)

Why only Nikon, you can get better DSLRs, and cheaper than $800 - the Pentax K-50 springs to mind.

Any DSLR with 18-55mm standard zoom will get you started, but you'll need either extension tubes or a macro lens for close-up work.

The easiest way to answer is this: The camera at any price is the one at that price. There's only one Nikon at $800 price point, which is the D7100. Yes, there are kits available with other camera models, but the best will be the most expensive.

Now, whether you actually need a D7100 or would be just as happy with a D3200 is another question. If the D7100 has features that you won't use, then you're wasting money that could have been spent on a better lens. Using a better lens on a cheap body is going to produce better image quality than using a cheap lens on the most expensive body. Therefore, you should invest more into lenses than the body itself.

For macro, I'd get a macro around 90-105. The Tokina 90mm macro is a fantastic lens. Go to photozone.de and check out their reviews.

For landscape, you'll want an ultra-wide zoom like a 10-20mm or something in that range. There's a large variety of lenses at a wide price range, so using photozone.de will be very helpful in finding the right one for you.