Amtrak is just so relaxing and scenic, especially through south OC and north SD county, where it passes along the coast for several miles between Dana Point and Del Mar. The traffic between LA and SD can vary from mildly bearable to horrific, depending on the day/time. I chose the train every time I can and never regret it. Business class comes with free drinks and snacks. The snack box has been pared back, but the drinks include beer/wine. Some of the Surfliner trains even have an observation car attached, but they will all have a cafe car.

For SD, it really depends where you are going. Both Old Town and downtown stations are also connected to the light rail lines in SD, which makes much of the area within easy reach via the Blue and Green lines.