The Los Angeles night life is its own unique animal in a number of ways. Things here are spread out and it is not logistically possible. Depending on where you choose to go out, you pretty much have to accept that it is your destination for the evening. Sure, in places like Santa Monica, Venice or Hollywood there is more than one bar per neighborhood, but generally the same people are mostly moving between these same bars. So, if you get somewhere and decide you want a true change of scenery, you probably have to travel. Everything in LA is about 20 minutes apart (stock answer from locals for visitors). Also, in places like Hollywood moving from one club to another is not always that easy or quick because of door policies and lines.
For people visiting and don’t really know people in LA, it could be difficult when comparing to other cosmopolitan cities like SF, NY, Miami, London, Hong Kong, Bangkok