But seriously, can you narrow the field a little bit with any preferences you might already have in mind....public, private, outdoor, indoor?
Two places that pop into my mind are the Getty Center.....so many beautiful views, they can't all be occupied at once, and Santa Barbara.....always a nice place to go back to and reminisce. (I got married there.)
Santa Barbara is lovely but it's a 2 hour drive north of LA.
Rattling off the touristy spots: Griffith Observatory (the Hollywood sign), Santa Monica Pier, Pt. Dume in Malibu (Baywatch), and anywhere in Beverly Hills (movie stars).
Some not so touristy ideas: the County Arboretum in Arcadia, the cliffs in Laguna Beach (nicer than Malibu and not as crowded), the Huntington Library in Pasadena, and, yes, the Getty Center.
For more than that, you need to narrow the possibilities a little.