Looking for reccommended settings

YugiStardustITA​  I've merged your posts together since they're both performance-related, and the same out-of-resources condition can cause both crashing and Error 12.

Please open this save, let the game clock run for a few sim-minutes, put it in windowed mode (don't alt-tab from fullscreen mode or minimize it), open the Task Manager, and see how much RAM Sims 3 itself is using.  If you're seeing percentages, right-click the Memory header to switch to absolute values.  Then play for at least 20 real-time minutes and check again.  Let me know what you find.  At that point, you can initiate a travel transition if you want, and watch memory use as the game is loading the new world and possibly crashing or erroring out.

Please also let me know if your system overall is over 90% memory used, and in that case, how much RAM you have installed.

As for traveling, there are steps you can take to try to help the game through the transition if it's ever failing then (as opposed to only sometime after the sims arrive).  Aside from quitting and reloading after your sims arrive, you can do the same beforehand, so the game barely runs before you send your sims away.  It also helps, here and in general, to disable memories, which are a massive resource hog, and the interactive loading screens, which use a bit of extra RAM.  And putting the EA App in offline mode may help too, although that's not clear.

Beyond that, the question is how frequent the crashes are and how inconvenient it is to quit and reload.  Lowering the graphics settings to the minimum just before travel can help too, but some settings need a quit and reload to take effect, or to not bork the graphics in the current play session, so you'd still be reloading twice, once when lowering the settings and once when restoring them.