Since buying the PMDG T7 I've been obsessed with long haul ETOPS routing and flights. I use PFPX to prepare all of my flighplans and export them to ASNext, the PMDG flightplan folders and the root FSX Flightplan folder. I am so impressed with this planning package and finally understand the complexity of dispatching heavy metal to far flung areas of the world. PFPX's fuel and weight routines return realistic weights and balance to the aircraft FMC and if one follows the rules, recommends trip fuel and reserves that are spot on.
 
ASNext adds exceptional realism to the weather planning aspects of long range flight including the effects of polar travel on fuel temperature and the problems and solutions available to overcome it. ASNext also provides complete and comprehensive weather briefings including altitude winds and temperatures that can be directly imported to the T7 via CDU. It also provides realistic multilevel cloud cover, ground fog and precipitation in the FSX graphical world.
 
Finally, I load AivlaSoft's EFB for terminal procedure selection and flight following. The EFB dovetails with PFPX and ASNext and provides all of the planning , comm and flight following tools available to the real world pilot. AivlaSoft EFB requires a small data unit, called the DataProvider, on the FSX machine and allows the user to install unlimited DisplayUnits on networked computers, second monitors or on an iPad via AirDispay. The DataProvider converses with FSX via simconnect and runs as a separate instance on the FSX computer. It has a small memory foot print  outside of the FSX VAS.
 
In the past 72 hours I've flown:
   KJFK-PHNL (New York Kennedy to Honolulu);
   PHNL-KLAX (Honolulu to Los Angeles);
   KLAX-KJFK (Los Angeles to Kennedy);
   KJFK-YBBN (Kennedy to Brisbane Australia).
 
These trips totalled over 16,000 NM and over 37 hours. Now here's the strange thing - I flew these legs consecutively with two to four hour turn times without a CTD, BSD, hard drive hang or graphics freeze. All were logged within a single FSX session with VAS never exceeding 2.8Gb. I turned most of the FSX and addon scenery on and off via SceneryConfigEditor between legs and had most of the FSX sliders all the way right. I did turn off all AI to ease CPU-Graphics pipe loads but still maintained an LOD_Radius of 7.0. Framerates were locked in FSX.cfg at 30fps and the sim ran at 28-30fps everywhere except KLAX and KJFK where I loaded FSDT's airport scenery. Framerates dropped to as low as 15fps while the FSDT areas were active - a typical condition for me when loaded.
 
The remarkable part of this experience is that I haven't "tweaked" the sim in over a month and in that time, I've only suffered a couple of CTD's that I traced to heavy scenery use and AI traffic. I use MegaSceneryEarth at the terminals and GSX North America in between. This unloads the FSX VAS and you can't see photorealistic scenery from FL350 through the cloud deck anyhow.
 
From a hardware standpoint, my i7 2700K has been rock steady at 4.6GHz and 48 degrees C. I can OC the chip to 4.8Ghz but haven't seen any improvement in FSX so I backed it down to reduce the load temps. I have a modest EVGA GTX 560ti graphics card and it seems to be well matched to the CPU at 4.6Ghz. I have 16Gb of PC3-12800 memory and an ASUS Z77 mobo. It's been more than three months since I touched the system hardware settings.
 
As you can see I put a pretty significant load on the system yet seem to have hit the sweet spot in tuning and tweaking the system. Has anyone else found themselves flying more and tweaking less?

I've been doing similar flights in the CS 777.  I've been using EFASS and it's pretty good.  There was some change recently so NAT waypoints don't get exported--a good learning experience on the FMC.  I've had my i7 920 for several years now and just really never used it that much.  I did upgrade my video from GTX 260 to the GTX 560ti a year ago.  Though I'm getting interested in a new system.

 

I'm on my second round the world starting at JFK.  I've done JFK - HECA, HECA-WSSS, WSSS-RJAA, RJAA-PHNL, PHNL-JFK.  There was JFK-EGLL-OMDB I think mixed in there once too.  Now I'm in YMML.  I was thinking of visiting all the top VATISM airports http://stats.vatsim-germany.org/topairports.php?sel=all

 

I'm trying to figure out how to incorporate the southern countries more.

I just completed New York to Zurich. No problems but my VAS jumped to 3.2Gb. Have to figure that one out because all I loaded was FSDT Kennedy.