Best Everything in LA?!

My boyfriend and I are visiting LA in March for about 4ish days. I’m working on our itinerary and want to fit in as much stuff as possible. Food recommendations such as breakfast, lunch, dinner, coffee, desserts, etc! We are not picky at all. Really love Asian, Mexican, & Italian… but would love to try new stuff!!! Museums, parks, monuments, hiking trails. I love museums + art, history, & science. We also love the outdoors and being active! Shopping centers, souvenirs, local small businesses. I love shopping and am hoping to find a nice shopping center + some cute places I can get stuff for people back home, and support local businesses. We also want to see the water! I would love to go to a few beaches and am willing to drive up to 45 mins, what are the prettiest ones? Please give us everything! Is there anything we should book in advance, must sees, or have to dos! Would love to know just any cool spots that would really complete our trip.