Thanks for the replies. I was looking to park the tandems and locking them a lot closer to the main entrance off the parking lot. The Macgregor entrance is closed on Fridays, and Miller theater is also a bit of a hike to the main entrance. I have noticed a lot of unsavory characters in the Herman park area in the past, and parking and locking "off the beaten path" would make the bikes more susceptible to crime, would it not? (giving criminals more privacy and time to work).

Also, our trailer converts to a stroller, so I can attach the front wheel (which folds out of the way for cycling) and then push it as a stroller around the zoo with us instead of locking it up. Then I would just have the two tandems to lock up. I assume I want to remove any and everything easily removable, like velcro strap mirrors, bike computers, water bottles, and even bring helmets in with us. Didn't think of all that. I'm a park and lock noob. Maybe staying with the tandems is still the best alternative.

If I couldn't enjoy my time in the zoo wondering about the safety of our bikes I think it would be best to just stay out with them.