An ebike and a trailer is also a fine way to go (could be one of the shorter length cargo bikes, like a Tern GSD or just a regular ebike). I've been very happy with my Stromer. Admittedly, I didn't get it until we just had one child who needed assistance ... we used a weehoo (but that doesn't become a viable option for you for a few years).
In retrospect, our original burley "twin" would have been worth keeping for it's use as a cargo trailer. I've would up buying both a cargo trailer AND a travoy ...the former for Costco trips, and hauling my folding bike ... the latter for smaller store runs ;>