Unmanned air systems (UAS) have numerous military, law enforcement, and commercial applications. Commercial potential in particular will not be realized until a comprehensive strategy is developed for safely and fully integrating UAS into the national airspace system over both rural and urban regions. This paper overviews a broad spectrum of UAS commercial applications to motivate airspace integration. Focus is then placed on use of small to micro-scale UAS in potentially lucrative but ultimately challenging benchmark applications: on-demand surveillance over a densely-populated urban region. Following the introduction of urban use cases, we present alternative criteria for small UAS safety that focus not on vehicle preservation but instead on avoiding collateral damage to people and property on the ground as well as to higher-cost airborne assets. We conclude the paper with a discussion of safety preservation when a micro air vehicle over an urban area encounters turbulence or wind shear, a likely day-to-day scenario that can introduce significant risk of a forced landing given realistic constraints on disturbance rejection. This study, led by Raytheon, is part of a NASA Research Announcement activity for Integrating Advanced Concepts and Vehicles into NextGen.