Hi @grant_2 & welcome to our forums!
That’s a very cool rendering already - the custom skybox fits quite nicely! Some suggestions from my side:
set the opacity of the window glass materials to 0% - that will make the windows looks more realistic (if you’re not aiming for that frosted glass look)
the sun light appears quite harsh - maybe you can try reducing the intensity a bit (Atmosphere tab → Sun brightness) to better match the surroundings
maybe add some color variance to the building design? it looks all very white right now 
To get a more realistic look you can also experiment with roughness textures - they can add a lot of detail to the surface appearance and will thus reduce that “consistent” CG look of materials.
Hope that helps! Looking forward to your progress :thumbup:
Thanks for the ideas, I made some of the suggested changes and it looks better.
I had a hard time with getting the sunlight to look right - it either seems to bright or dull but I’ll keep playing with it. The skybox images I tried all display below the model and I couldn’t figure out a way to raise them up to look better but I saw some others mention this. I got it to look okay.
Here are some updated renders.
