I am looking for the perfect all around commuter/kid bike, that I can throw in a unlocked garage and not worry about, that I can put a kid seat on, that I can just cruise to the store with my flip flops, that says I am a cyclist, that I can ride on a rainy day and not get too wet, and that can go off road on light dirt paths if wanted. I am thinking I may have to build a single speed cross bike with fenders, any suggestion on a frame that can be had fairly inexpensively and can be built into what I am looking for?