The port of LA is a joke, but don't worry, I have yet to see any port except maybe Vancouver that isn't a joke, at least from the outside. As for taxi fare, I don't know, about 5 years ago it ran in the neighborhood of $35.00 but am sure it is much higher now. I would suggest you see if you can get another couple to share with you. You might even meet someone at the hotel the night before, who knows. Anyway that would be the least expensive way and kinda nice to get to know someone before sailing.
Good luck and if you have any questions I am sure we would all be glad to answer. NMNita