Weather, weather, weather. The "silicon beach" is 10 to 15 degrees cooler than downtown on a summer day with noticeably less smog. For many the west side is where its at,
To the previous commenter's point: Culver City has it all in terms of food, rental space, and access to the (albeit lacking) LA Metro.
Do you exercise outdoors? Would you seriously prefer to run at Griffith Park rather than on The Strand?
When I lived in LA, everyone who preferred the weather east of the 405 didn't exercise outdoors (if at all). They would ask, "Isn't the weather beautiful today?" after walking for less than 30 seconds from their air conditioned car to our air conditioned office.
(I've long since moved from LA to the Pacific Northwest, where I can work up a comfortable sweat hiking Mount Rainier.)
There is a stretch from Aug to Sept or so where I need to be done by 11am (or start late afternoon). Every year is a bit different though... sometimes there is not much of a winter, sometimes the summer is mild, sometimes almost hellish... luck of the draw I guess.
In any case I can usually count on about 3/4 of the year being sunny, 80F, and low humidity. I've traveled but have not seen better.