With the increasing numbers of sensors and smart devices being deployed worldwide, the volume of data they generate is becoming difficult to store and process on local platforms. Cloud computing provides scalable resources that could address these issues. However, platform-independent methods of gathering and transmitting sensor data to Clouds are not widely available. This paper presents a survey of Cloud-based sensor monitoring and data gathering platforms. It reviews the state-of-the-art and discusses their strengths and weaknesses. Informed by the survey, the paper further proposes a generic conceptual architecture for achieving a platform-neutral Cloud-based sensor monitoring and data gathering platform. We also discuss the objectives, design decisions and the implementation considerations for the conceptual architecture.