Last year my wife and I walked across the San Diego-Tijuana border to have a nice dinner for our anniversary. This year we met friends and walked across with our kids during the day. We took a taxi to the Centro Cultural Tijuana, which was cool. You get a different view of Californian (and US-Mexican more generally) history.
In this era of xenophobia, it's worth of it for that alone.
But then we just walked, found some good food, and checked things out. Yes, it is touristy, but Mexico needs tourists and a reminder that Tijuana is a place to take your family. People could not have been nicer. If you visit San Diego, then just park at the border and walk across. If you take the new Pedwest pedestrian crossing coming back, it's really quick.