as long as you dont plan on leaving downtown LA you can take a cab anywhere you want...if you want to go check out hollywood or beverly hills then you can take a bus in for the day as a cab would prolly be a little pricey due to sitting in insane traffic. downtown isnt HUGE like midtown NYC, but the whole area including hollywood and beveraly hills and the beaches are pretty big however if you want to leave LA then you must have a rental, the traffic in the LA area is no joke, and traffic jams are nearly and hourly not daily experience.

hope this helps.