One of the best places to visit in Tijuana is Parque Morelos. Plenty of green grass, trees and a lake, which is a combination you won’t find often in Tijuana. Best of all it is free, and if you drive I believe the parking is 20 pesos which is barely over a $1. They have picnic areas, lots of animals, you can feed ducks and have a few carnival rides as well. Food is dirt cheap and their is a lot of options. There is even a small train that circles the park and you can get your pic taken with your friends and buy a key chain for next to nothing. Here is a link that has some pics: http://www.descubretijuana.com/en/attractions/parks-and-resorts/parque-morelos
Their is a Cultural Center in Zona Rio called Cecut and I cannot even tell you what is there, but it does have a small aquarium that the little ones love. I believe admission is like $4 per ticket and their is the Domo Imax that is quite popular and every now and then their are music or food festivals that are there. Here is a link for that as well. https://www.cecut.gob.mx/
There is a Wax Museum in downtown Tijuana just off of Revolucion on First street (Articulo 123) and it is bit East and easy walking distance from the border. I believe admission is less than $5 and as much as I loved the place it can be brutal in the Summer as it is not air conditioned. I like to visit in November. Here is a link for that as well. https://www.museuly.com/listing/tijuana-wax-museum/
We have great sports teams around town. The Toros play in the professional Mexican Baseball league, while the Tijuana Xoloitzcuintles (pronounced like Cholo Twiklies) are in the professional soccer League and are in the first division. The Zonkeys are our Basketball Team and they normally have 2 or 3 Americans on their team. There is a rule limiting the number of foreign players per team. Sorry I cannot tell you much about it as I have never been as my job makes it difficult to go to a game. I have however visited with a few of the players as I use to live near where a couple of them lived and had run into them at a pizza buffet a few times
The malls have first run movies for very reasonable prices as I believe they are maybe $4 per ticket. I normally buy a package at Costco that gets me into 10 movies for about $20. Normally they are in English and subtitled in Spanish. There are a couple of theaters at the Plaza Rio and I like the VIP which is still pretty inexpensive and you are assigned a seat and waiters take your snack order. I normally pay the person who takes the order and then tip the person who brings our food.
I hope some of this info may be helpful, but believe me there are plenty of things to do that would cost so much more in the United States. Bring the kids and I promise they will have fun.
Should be back real soon. Be careful out there.