incredibly useful default scenery found!

[jbird]

I was flying my Alphasim A-10 just N.E. of San Diego. Suddenly to my right I saw the most beautifully flat unprepared landing area ever! It is in a basin just past an area called Lake Riverside Estates. This field must be 2 miles across, no obstacles, perfectly flat. My A10 landed with no problem in it with room to spare.

[KDSM]

Yeah there are lots of places like that.
get an object placer and make your own "secret base"  ;)

[Tweek]

Find the Bonneville Salt Flats in Utah. That's great for speeding along in any ground vehicle you may download! There's a landclass file for it somewhere (I think I found it on AVSIM) which makes it look white, like in real life.