^^^ This. I was thinking the same thing...
@Peter Ha, don't worry about other people talking about what *they* can do with a 150. Learn what *you* can do in *yours*.
To become master of the "cool short/soft mountainy places", involves three very different kinds of skills: a) knowing your airplane's performance, b) dealing with soft fields, and c) dealing with mountains.
You can practice (a) by going to *any* runway for some pattern work and taking note of how far it takes you to take off and land. Use the runway stripes as a reference -- it is 200 feet from the beginning of one centerline stripe to the beginning of the next one. Over different practice days, try to notice how the answers change with temperature, field altitude, and weight.
You can practice (b) by going to an airport with a nice grass or dirt runway but that doesn't have a lot of other challenges (like obstacles). I don't know of any in SoCal, but I'm sure someone on this board can make a recommendation... Take a CFI with you if you're at all uncertain about this. Take note of how all the numbers from experiment (a) change when the surface is soft.
You've already gotten some experience with (c) on your epic cross-country... so you already know that negotiating terrain is its own challenge, irrespective of the runway. So fly in and out of some mountainy places that have nice long paved runways, but are in mountains or valleys. I'll throw Kern Valley (L05) as an example near you; it's beautiful, has a great airplane-campground with showers and everything, and a breakfast/lunch cafe on the field. The runway is plenty big, but it's nestled in a valley and you'll have to be "inventive" with the traffic pattern because there's a hill that sticks up right into where the downwind-to-base turn would be. SoCal experts can (again) maybe chime in. Columbia (O22) is farther away for you, but another really great mountain airport. Be mindful of the winds and up/down-drafts. Maybe take a "mountain-flying" course with a CFI, for tips.
Eventually, when you're comfortable with (a) and (b) and (c) separately, you can start combining them together. Expand your comfort zone, but one step at a time. I live in Alaska, and flew a 150HP 150 for a while, and I am still slowly expanding my own short/soft/mountain comfort zone.
Have fun!
