Hi Steve,
First of all, WELCCOME to NPN! Glad to have you here and that you’ve joined the community. As Marylynne mentioned, lots of Yosemite afficianodos here, including myself.
This is classic - and in a couple of ways. A classic viewpoint off of 120 coming in to the park. I love how the mountains and monoliths are compressed together - ie. Half Dome and El Capitan. This is also classic really in the definition of the “blue hour.” Also a classic exposure challenge! With the sky just getting brigher with each passing moment, the landscape is left in shadow for quite a while.
I think you did a great job composing this. I also think you handled the exposure well given the dynamics. The challenge comes in how best to process the image and portray the colors as best you remember and experienced. The good news is, when it comes to color/saturation, etc., it’s very subjective and often personal.
I think the colors in the sky above half dome, the pinks, lavenders, etc. are just about perfect and quite natural. For me personally, it’s the blues that are the challenge. And actually the blue in the URC, upper right corner, looks pretty good. It’s the ULC corner that is drawing my eye and thus distracting. It almost looks like there’s some vignetting going on, but with a longer focal length, I don’t see that happening. Anyway, my suggestion might be to process it in such a way that the two upper corners are much closer in color, saturation and luminosity. One clue is that direction, east, is where the sun would be rising and I wouldn’t think from this vantage point there would be a difference in those two corners.
The “blue hour” light/color on Half Dome is a little more realistic, but again a personal choice. I might dial back the blue a couple of points.
It’s hard to tell, but lastly it looks like El Cap and the foreground ridges are lacking in some detail. I expect possibly it’s the jpg compression and/or the size you posted? Hopefully you’ve got a good raw file where more detail might be present.
Hope this wasn’t too harsh. You’ve got a gorgeous sky. I think with some tweaking the rest of the image could be made to match the greatness of the sky. Hope that makes sense.
Welcome aboard! We look forward to you images and participation!
edit: your comments explain a few things… 
