Hi Doug,
First off – what a beautiful spot and composition you’ve chosen!
Regarding the processing, I do and have done quite a lot of editing in the style that you describe (although most often the other way around, subtractively rather than additively, and not for colour landscapes). For colour photos, and perhaps high(er) dynamic range landscapes especially, It is really hard to achieve a good looking result. I feel that one has to be much more careful than with black and white editing, as it’s very easy to end up with a photo that looks unrealistic or “off”. I also think that it takes a lot of practice and patience.
Push things too hard and it’s quite easy to end up with oversaturated areas with this technique, but you’ve done a great job in that regard, apart from having different contrast ratios and saturation in different part of the image (most notably center and foreground vs. the trees).
apart from that, I really like the contrasty yet soft look that you’ve achieved with those trees. In a broader landscape, like this photo though, I feel like the contrast between them and some of the much more flat parts, like the mid ground water for example, is too great, creating an imbalance in the photo.
In my experience, while the gradient tool (in Lightroom, I assume?) is very convenient, it is also very imprecise and is very hard to use with shapes found in landscapes. In instances like this, I mostly use it for lighter and often broader strokes, and almost always combining it with the Luminosity (and/or Color) Range tool (either intersecting or subtracting) or the brush tool to make it look more natural. The Ai subject, object and sky masking tools can be very helpful here too.
The last area that I think needs a little more love is the sky. While the clouds look good, the blue of the sky looks a bit oddly dark and moody in some parts. Where you’ve dodged the trees on the left, the open sky looks much brighter around it, compared to the area to their tight. Similarly, the middle and right background trees also look a bit off. You’ve dodged them in their lower half, letting them grow distinctively dark when crossing into the mountains and the sky. The solution to this lies in luminosity masking, but if you want to keep your editing in Lightroom, the newer masking tools as well as the inclusion of the curve tool there will often help a lot.
I also think that when you select the spots to highlight with this technique, you should try to do it in a way that connects those spots so that they create a path for the viewer’s eye to follow through and around the photo (sort of like leading lines) and not including the nice foreground seems like a waste, turning that part of the composition into “dead space” (connects to @Igor_Doncov’s suggestion.
And lastly – you’d gain more dynamic range and a higher noise ratio by not underexposing in camera (not that this looks bad in any way at this resolution and size). As long as you don’t blow anything out, you can always pull down the exposure as a starting point in processing. Now if you shoot with the very best cameras in terms of dynamic range (middle format or the best FF cameras in this regard), this might be less important, but still – optimising the image quality of your RAW file gives you the best possible potential in the end.
This will also give you a better starting point to try the reverse technique to the additive processing that you’re employing here, (which I feel tends to work better for landscapes), dodging a normal exposure rather than burning a darker one.