SNA isn't any big deal particularly, but the airspace around L.A. is generally busier and more complicated than the others you mention. Be sure to study an L.A. terminal chart beforehand and use flight following to enter the area. Where are you flying from?
Flying into SNA in a 172 was probably one of the most fun flights I've ever had. Got to land parallel to a SW 737, just have to remember your wake turbulence avoidance procedures. The run up area for 19L is actually at mid field about at the end of 19L/beginning of 1R. Other than that is isn't any scarier than any other Class-C Airport.
The best advice I can give is CAUTION WAKE TURBULENCE, CAUTION WAKE TURBULENCE, CAUTION WAKE TURBULENCE, and Go around, go around, and go around!!! More than a few have died because of it at this airport. But other than that, I think we have some of thee nicest controllers on the block. Very helpful to unfamiliar pilots!