To all those who are saying, essentially, Santa Monica or bust... Not really. (For the record, I <3 SM and want my first house to be there.)
Where you work should have a big impact. Santa Monica to DTLA is TORTURE. That said, DTLA is expensive in the non-shitty areas.
For DTLA jobs: Pasadena (if you take the Gold Line), Los Feliz/Silver Lake (if you don't mind hipsters), or some parts of Hollywood (like Larchmont Village, etc.) I go to school downtown (Loyola) and live in the area between Culver, BH, and WeHo. It's equidistant to both DTLA and the beach. Save BH or a place in SM (commute and all) for when you have some financial stability and/or less loans.
For Century City and Beverly Hills firms: Culver City is a very good option, as are some parts of WeHo and WestLA. At this point, Santa Monica, Venice and Marina del Ray also become realistic. The Beverly Hills Flats (i.e., south of Wilshire) can sometimes be reasonable, but at that point you're paying for the BH name and not much else. Studio City and Van Nuys wouldn't be terrible, but I'm not a fan. IMO, the valley is where you go when you are 45, have a spouse and kids, and want to buy a large house in Calabasas/Hidden Hills.
For Santa Monica jobs: Duh... Maybe WestLA, Palms, or Westchester if you want some distance, although there are few good commuting options from there; Lincoln, the biggest North/South thoroughfare in that neck of the woods, is killer even in the off-peak hours. Don't commute from El Segundo or the rest of the Southbay unless you have a DAMN good reason (like a spouse).