I have a Schwinn. It has a third wheel for the front to use it as a jogging stroller, but when it is behind the bike the front wheel comes off. I liked having the third wheel because I could ride the bike to the zoo, take the trailer off the bike, put the front wheel on and push the trailer around inside the zoo when they were little. I still use the trailer to transport stuff now that the kids ride their own bikes. I can put folding chairs, picnic lunch, soccer balls etc. in it.
ETA: I am only 5'2" and 125lbs and I never had any trouble pulling the trailer with both kids in it. I still had them in it for long trips when they were age 5 and 2.