My husband and I were very impressed with this wonderful day tour of Tijuana, and we had a super fun and memorable time. We took the Blue line trolly from San Diego to the border and it felt quick, easy and safe. As others have mentioned, your guide might let you know in advance if you need to meet on the Mexico side of the border. We got that notice and found it surprisingly simple to meet him right on the other side. There is really only one way to go as you cross, and he meets you at the end of it.
Our guides were very organized and knowledgable - they showed us all of the sites while explaining the history and significance. The history was mixed in perfectly throughout the day with stops for a wonderful lunch, an alcoholic beverage if you like here and there, and shopping if you choose. We had a nice group of about 16 fun people from all over the world.
We felt self and had no safety worries. The guides spoke loudly so the whole group could always hear. It was easy to stay together and they consistently did head counts. It was an amazing place to see and this was definitely a highlight of our San Diego trip!