I live in LA and do the following for friends that come over:
Malibu - drive to Malibu Seafood and run across the PCH to eat it on the beach
Santa Monica Mountains - tons of amazing hikes and then have lunch in the Pacific Palisades
Venice - morning walk around the canals, lunch on Abbot Kinney (Plant Food and Wine is my fav restaurant in all of LA) then hit up the beach and boardwalk
DTLA - go to the Broad Art Museum, have lunch at Grand Central Market (vegan ramen is amazing as is the horribly overpriced macadamia nut milk lattes) then take yourself on a walking tour of the amazing buildings (keep out of Skid Row but the Fashion District is worth a punt). Stay on for evening cocktails at Perch and maybe catch a concert at the Walt Disney Comcert Hall
Pasadena - old town is lovely and great places to eat and drink, but spend a chunk of the day at the Huntington Library and Gardens. If there second Sunday of the month check out Rose Bowl Flea Market
South Bay - do a wee tour of the beach communities (Manhattan, Hermosa, Redondo) and check out in advance if going on the weekend because there’s usually a festival or volley ball contest going on which is fun
Go to the Getty Museum then do Mulholland Drive to the Observatory and do that
Steer clear of: Hollywood (it’s a shit hole), Santa Monica (so whitewashed and traffic is a nightmare), the Valley
We’ve been here for 6 years and have done universal once and Disney twice, there’s so much more to see and do including tons of galleries, loads of lovely beaches, hiking, biking, great food, vintage shopping