Many current endeavors dealing with IoT and Cloud topics suggest leveraging sensing resources as mere data producers whereas the authors follow a Sensing and Actuation as a Service (SAaaS) approach. Among core ideas of SAaaS there's the enablement of an Infrastructure-oriented (i.e. IaaS-like) provisioning model for sensors and actuators alike. Such model matches technological requirements and constraints arising within certain application domains inspired by research about Future Internet topics. Aim of this paper is to explain why adopting the SAaaS paradigm for pervasively available and geographically distributed IT infrastructure is key, especially when field deployment of custom functionality is needed. Smart devices featuring always-on connectivity are the backbone of the IoT vision, and core building blocks of such infrastructure. Cloud-powered monitoring of urban areas and public facilities are among the most compelling scenarios to be found in IoT, and we are here focusing on these scenarios for two use cases. Actors, workflows and activities are described here in order to explain the main interactions and follow through outlining the use cases.