I live in Pasadena and drive to/from LAX quite often.

First, it's possible to get from LAX to Pasadena without your own car, but there's no perfect (IMO) solution.

The most convenient would be a taxi, which would cost close to $80-100, including tip.

Next would be a shared van such as SupperShuttle or Prime Time, which would be cheaper, but could involve some waiting, cramped seating, and lots of stops before your hotel.

One can take the LAX Flyaway Bus from LAX to Union Station and then take the Gold Line (light rail) but that would involve some schlepping of bags, especially from the Gold Line to your hotel.

If you rent a car, the are a few routes that I take, depending on the time of day and weather. Sometimes, the most direct way (105 to the 110 for you locals) isn't the best when you factor in rush hour traffic or rain.

In general, one will need a car and a good freeway map to travel in LA, especially if you plan on going to more than one location.

Let us know which of these sounds the most likely you will choose and we can take it from there.