We were having our baby moon and wanted to take a quick trip into Tijuana as we'd never been. After looking at doing it ourselves but given our lack of Spanish and not being familiar with the area, we decided on border tours as a safer bet. This turned out to be an awesome decision. Tadeo, our guide, texted us about 30 minutes before to tell us he'd be meeting us on the other side. After that, he bundled us into a taxi and took us on a through walking tour of the town with lots of historical anecdotes. We were then taken to a taco shop with some of the best chorizo tacos I've ever had (I live in an area with many first generation immigrants from Mexico, so we've had some bomb tacos), followed by margaritas at a beautiful terrace, and then tequila tasting at a cute shop. We were then given about 30 minutes to browse around some shops before being escorted back to the border. Absolutely wonderful day. Tadeo took tons of shots for us and took good care of us when we wanted to grab one of those silly tourist painted donkey photos. He was very knowledgeable about toilet location.
To give people a context of the hours, we arrived in Mexico (no wait at border) at around 1:05pm and was back in the car by 6:05 PM. I'm about 8 months pregnant and had no difficulty with the walking. There's a parking lot right across from McDonalds where the border entrance is that is about 12 or 8 dollars for 8h. I'd say its about a 10 to 15 minute walk max from the lot to the meeting spot on the Mexico side.