Choosing a bike for toting a baby

Hi all, first time poster here.

I have a sweet, sweet mixtie that I love, which I cannot attach my iBert t0. This is my chance to get a new bike, something along the lines of a grocery getter. Long wheelbase, smooth ride, total weight, what else do I need to consider?

We already have the iBert. My daughter is a year old and 20lbs. I LOVE hub gear bikes, but have trouble finding them. I'm in Cambridge MA.

My budget is flexible, but I'd rather find something under $200.