We have the trailer from Costco, and it's awesome! It carries two kids, has space in the back for a diaper bag or lunch and converts to a stroller. It's easy to tow around, even with my 1 and 3 year olds in it, and they seem to be strapped in tightly and fairly comfortable.

It is also easy for me to fold down flat, convert to stroller, hook up to the bike, take apart and generally just maintain.

I think it's called a kid-a-rooz or something, and it runs about $150.

Tamara