Those screenshots are fantastic, Stephan, and I would love to see you post more here! Speaking personally, I'm too lazy to mess around with any post-processing (just snap and share), but I do enjoy playing around with the weather settings in the sim as they can so drastically change not only the contrasts, but the overall colors as well (not just time of day, but the amounts and locations of clouds can have a big impact on the colors too).
Here are some screenshots flying from Land's End to St. Mary's on the Isles of Scilly - both exceptional freeware addons by Superspud, just recently updated again on Flightsim.to
In addition to always making sure I check through all of the latest releases on Flightsim.to, at least once a day, I've had to get in the habit of checking the recently updated section each day as well, as some of my favorite addons, such as these shown, are continually being updated and improved upon over time, and the updates don't show-up in the "recently released" section.