With a carrying capacity of 300 pounds, the Supermache bike ($2,600) could theoretically replace a second family vehicle and be used for grocery trips, kid drop-offs, Home Depot runs, and everything in between.
The bike comes bare bones, but Yuba offers lots of bolt-on accessories, including a baby seat and gear-hauling wooden tub. Just the frame weighs 58 pounds, but thanks to cable-actuated steering and nimble 20-inch wheels, it handles reasonably well. A double-wide kickstand keeps it steady for loading and unloading.
All that said, if you plan on consistently carrying 100 pounds or more, we'd suggest adding a mid-drive electric motor.