Took my son who is just shy of five to the track last night to try it out. The staff at the track were excellent. At sign in they walked us quickly through the process and gave us all the pertinent information. They helped both my son and myself get equipment from the rental room and we were off and riding within 15 minutes of getting to the track.
In addition to the staff being great all of the riders and other parents at the track were really great as well. My boy snuck off and another parent helped him get prepared and launched him from the starting gate. Everyone was really supportive and there were lots of encouragement from everyone. Nobody was upset when my 5 yr old boy lined up beside them to race the track.
The track itself was a lot of fun. I'm just getting into bmx (at 40) and I had a blast. Both my son and I were able to ride at our own pace and get comfortable with the track.
One side note, bring your own drinks as the snack bar is not always open and you will work up a thirst riding the track.
If you are looking for something the whole family can do, I would highly recommend coming out to the track. You can follow the track on Facebook and they do a good job of posting the track schedule and up coming events. The track has rental equipment so you can try some different types of bikes before you invest money into them.
Overall we are looking forward to starting out racing careers.