I came across a recent film on cargo bikes in Denmark that reminded me of the two months that Grace spent in Copenhagen in 2004. The photo here is from a neighborhood in Copenhagen called Christiania ("The Freehaven"), but we certainly came across them everywhere. We made friends with a family whose father regularly shuttled his two kids around in one that looked as comfortable as any stroller seen here in the US. Here's the short film:
http://www.streetfilms.org/cycling-copenhagen-through-north-american-eyes/
Unfortunately, we've still got a ways to go before I'll be comfortable with my daughter in our bike trailer on the streets of Seattle. I don't mind dedicated bike lanes, but sharrows don't do it for me...and seeing drivers texting on their phones while near me is unnerving.
It does seem there's a tremendous opportunity for American-made cargo-style bikes, which would hopefully make them more affordable (see CETMA, below). Obviously, even $3K is still substantially less than the annual costs associated with car ownership.
http://dutchbikeco.com/_product_77092/Bakfiets_Cargobike_2009
The hills of Seattle also dictate proper gearing...very, very low to get up some hills. Here's a pic of Ella & Julia outside of Velo Bike Shop on our way up to Volunteer Park.
This Equinox Trailer is still manufactured in Oregon, and I like the flexibility of the system that they've designed. My aunt & uncle have loaned us their trailer, but even though it's 20-years old, I could still get upgraded seat and hitch components that fit: