I've got a child trailer that I use on rare occasion. My company gives us a Thanksgiving turkey every year and I usually pull the trailer on that day to bring it home. The added drag is very noticeable to me so for myself I wouldn't want to pull it every day. Also, most days I ride my road bike but the trailer hitch is mounted to my hybrid bike, so I get the double speed-whammy.

I do notice that cars give me a much wider berth when I'm pulling the child trailer. At stop lights I get interesting looks when people see I've got a 20 lbs turkey strapped into the safety harness.