Originally Posted by PTravel

There are dozens of flights between LAX and SFO each day and, because it is a relatively competitive route, fares are reasonable. I once did this as a date when I was in law school. It is certainly viable to do a day trip. However, I would suggest less time in LA and spending at least a night or two in San Francisco, which is a much nicer and more interesting city. I would also recommend skipping Tijuana. Like most of the Mexican border towns, it is nasty, crime-ridden and dirty and not, in the least, representative of Mexico.