EDIT: Obviosly I’m late to the party - see posts below this one for more.
In case you hadn’t heard, there is a new De-noiser in Blender 2.81, and it’s pretty impressive. Setup is a little more involved than the Cycles de-noiser, but the results are impressive.
The new De-noiser is a node in the Compositing tree. You will have to add it between your Render Layers and Composite like this:
Notice that you will have to output a Normals channel as well as a Diffuse Color channel to feed into the Denoiser - this helps the De-noise algorithm NOT mash details - and here is where you turn those on:
You’ll have to render the image (F12) or the animation to see the results.
Here are some examples of the outputs:
And some render comparisons with samples and times:
And a comparison between 512 samples and 64 samples with the new De-noiser:
And another image with samples vs with and without De-noising
Notice that in the 32-Sample image, the Cycles De-noiser was slower AND gave worse results. Also, it seems that the De-noise added about the same amount of time based on the render dimensions and the complexity of the scene didn’t seem to matter much.
I hope eventually this gets turned into a single-button solution, but it’s still a very promising addition.
I hope this helps!