Researchers and commercial solution providers have at their disposal many different sensing options. As a result, more than one sensor type is usually available to measure a quantity of interest. Each sensing option presents its own unique set of advantages and disadvantages. These must be weighed in the context of the use case or application being implemented to determine which sensing technology should be selected. This paper looks at the key challenges and requirements for sensing in 3 key application domains: Environmental, Healthcare, and Wellness Monitoring.