I recently returned from a lovely and exhausting family vacation in New York City and Washington, DC. The trip was decidedly DIY. We used UberX for car transportation, AirBNB for lodging, TripAdvisor for daytime activities, Yelp for restaurant insights, HopStop for subway updates, and countless apps to inform our various activities. Essentially, each and every activity and dollar spent was somehow informed by the experiences of others who....