I don't know how it will fit your Dyno Cruiser, but by far my favorite is the Ibert Safety Seat.
I probably ride about 30 miles a week with a 2 year old on my bike, and I have used front seats, rear seats and trailers.
For long distance riding or riding with a sleepy child I like a rear mounted seat. They allow you to pedal the same as you would normally and allow the child to fall asleep without his/her head flopping around. Unfortunately though, you don't see your child unless you turn around, it's a bit harder to communicate with them and your child has a view of your butt. If you have a sprung saddle, then you also have a potential pinching hazard if your child has their fingers in the springs when you happen to hit a bump.
Front mount seats are MUCH better in terms of interaction, but tend to interfere with your knees. Even the Ibert interferes a little, but it's not too bad. They also tend to give little support to the child's neck and shoulders, so if the child falls asleep, (very common), they're either just flopping around with every bump or turn or you're trying to support their head with your arm while simultaneously pedaling and steering. Despite this however, the ability to easily talk, interact and point things out to each other is worth it. You can also immediately see if something is wrong. They're right there in front of you.
I hate trailers for children. I don't think they have any advantage in any way, including safety. They're heavy, they're too far away to talk with your child. You have three wheel tracks and are much wider. They put your child right at the eye level of dogs. I just don't like them period.
