Which city is a better vacation spot. atmosphere, general cost of restaurants, transportation
Can't speak to transport as I always get a rental which I would strongly recommend, LA traffic definitely sucks though. Restaurants are amazing, especially Mexican. Travel cost is near the same, San Diego is a bit cheaper. I adore California as a whole, it's my happy place.
I love LA for it's variety of neighbourhoods, everything is so spread out that each area has a unique feel and atmosphere. Santa Barbara (1.5hour drive but meh), Malibu, Venice/Santa Monica, Downtown LA, Hollywood Hills, Korea Town, Newport Beach, Silver Lake/Echo Park, and on and on. If it was only one "city", definitely LA.
San Diego has a much smaller feel and vibe to it, still great, just less variety of things. Coronado and La Jolla are highlights. Can walk/drive into Tijuana which is a very cool place in itself.
If you get a rental, you don't have to limit yourself to one city, there are a ton of amazing little spots everywhere. I normally fly into LA and drive around everywhere. Alternatively, I've done a couple fly in/road trips in the area, itinerary below
- Fly into San Francisco, Napa, double back and drive down the PCH (give yourself time, so many places to see) to LA, then San Diego/Tijuana. Double back to San Francisco on the interstate (smarter thing would be to fly out of San Diego)
- Fly into Las Vegas, south through Joshua Tree, Salton Sea, west near the Mexican border to San Diego, north to LA, back east to Vegas (once again, smarter would be just to fly out of LA)