I used to exclusively take the metro, the blue line to the red line. Depending on where you're taking it from I could tell you how long. It took me an hour total, from long beach to universal city.
With the red line though, I don't recommend taking it late at night, and certainly not alone in the evening. It can be a little rough sometimes.
Generally it's safe and very cheap. All day unlimited ride passes are usually $5. Way better than paying for gas and parking.