These few things will turn P3D into a new game:
https://orbxdirect.com/
Before anything else, get FTX Global(a re-do of the entire earth), FTX global vectors(re-does all the coast lines and river banks), HDTrees, and Open LandClass(will change all the generic areas outside of photorealism to the proper type of vegetation like farmland, forest, desert, ect down to 1/8th mile accuracy in most cases). This alone will totally transform your sim. Any other add-on from them is great quality, all of their different USA regions have great detail and they even spice up just about every airport in the included region. SoCal and NorCal look amazing but require a fast computer. Flightsims get most of their performance from the CPU, so a strong CPU with an okay graphics card will have much better results than the other way around.
Next, get the REX4+Softclouds bundle:
http://www.rexsimulations.com/texturedirectsc.html
What this does is pretty amazing, it allows you to pick from thousands of textures to make everything from the taxiway lines at default airports to pavement to the way the waves and water look with the click of a button and screenshots. You pick what you want the first time around and it will update everything, then anytime you want to change something, you go to that specific texture(clouds, sky, taxiway, grass, ect) and just click "install" on a new texture. Softclouds is an add-on to the cloud textures of REX that adds new multidimensional cloud types that look very real. Some are better to simulate marine layers, some are better for lazy summer days, some for building cells. They look significantly better than the clouds included with REX, which are much better than the default clouds themselves.
Lastly, ActiveSky for P3Dv4;
https://hifisimtech.com/asp4/
This is a new weather engine. REX gave you textures, but when you run ActiveSky, it takes over the weather from P3D and generates the weather itself. It has a live mode and a historical mode where you can load up the weather from any airport/weather station from any date in the last several years. ActiveSky adds all sorts of effects like much more realistic turbulence and wind effects(including wake turb off AI planes and up/down drafts), much better effects when flying thru clouds, and the clouds generate in much more realistic layers that make the sky come alive. It also comes with a basic way to customize weather by picking the airport you want to fly from and if you want a summer storm or winter storm and then you can keep hitting "generate" until you like what appears on the radar. They sell another add-on called "Weather Architect" that lets you paint up whatever weather you want in a very easy and user friendly way where you can make anything from hurricanes to ground fog appear very realistically anywhere you wish for your flight and set the change rate and all that stuff.
This clip is a good show of what the weather effects are like with this goodie.
And this is a clip of all of them working together in Prepar3Dv4:
One more thing, I'd suggest for you...
The TFDi 717 happens to be one of the most realistic add-ons for P3D.
https://tfdidesign.com/717.php
Someone did an AirTran repaint, too.
http://forums.tfdidesign.com/index.php?/files/file/24-tfdi-717-200-airtran/
Other than that, I can send you a care package full of goodies like a bunch of airports airplanes and, if you care, AI traffic. What sucks is since P3Dv4 is 64-bit and every other Microsoft/Lockheed sim was 32bit, most planes/scenery for other versions don't work yet since the developers need to re-code the products one by one, if they even do. But it is the way of the future. Just text me or FB message me or whatever with any questions you have installing stuff or if anything messes up.
