Let me say that ocicat is correct. Ideally, one should have a simple, easily-read and -maintained config file.
Having said that, I have had the same prompt for 10 years or so. The only time I had to delve back into the escape codes and ANSI colors was when I switched to ksh from bash. Once I figured out how to get the colors I wanted, I did not take the time to clean it up with variables. Shame on me and my laziness.
Once I get the time, I will probably do so. However, with the way my time has been lately, that probably won't be for a while.
But, yes, I advise to break the codes down into variables like ocicat said.