OK Joey.  Here's a few suggestions.  And yes in L.A. a rental is a MUST.  Public transpo sucks and the LA basin is far too vast to cab it.  You'll pay a fortune on fare.

Jerry's Famous Deli in Burbank, lots of Hollywood scouts and producers have lunch there so you'll see all walks of life trying to "look" the part as they hang out waiting to get picked up.  Trust me, you'll be able to tell who's the shot caller and who're the ones trying to get scouted.

Tommy's -  Corner of Rampart and Beverly.  This is the home of L.A.'s cheeseburger.  An LA icon.

3rd Street, in Santa Monica - A closed street with a collection of shops, bars and stuff. Great place to people watch.

Cruise Sunset Blvd -a must.

Manhattan Beach, Malibu - great beaches without the touristy feel.  Lots and lots of tail to see.  Just wear your shades so the mrs won't catch u.  If you can make it down the 405 fwy to the Orange County, head over to Huntington Beach.  THE BEST BEACH IN SOCAL!

You really don't need a car. Go grab dinner at STK which is on the same street as SLS (about 1/2 mile). Or if you want to get the best sushi ever take your woman to KOI...once again off La Cienega. Afterwards go to Coco DeVille which once again is off La Cienega....when you go there you'd wish you left your woman at home.