Hi Tom,
Clouds are found under the "weather" layer. Sunlight can be turned on (as long as you are using Google Earth 4.3) by hitting the button in the top row of icons (next to sky).
sunIconLocation.jpg
I agree with Gaieus' statement about context. I think all these things combined and you can produce some nice screenshots!
See ya,
Zach
Here's a day and late evening shot of Denver:
DenverShotB (Medium).jpg
DenverShotA (Medium).jpg