Hit counts will not translate to ROI or business drivers. Usage studies and interviews will give you better feedback on the system. If possible, it is better to determine your performance metrics before the system is built so a mesurable baseline can be determined. From the technical standpoint, it can be very computing resource intensive to measure usage. Web server can easily track hits and some tools will report trails.
Database servers can report transactions and loads.
Again, as above, it can be hard to understand what your measuring. You also need to find resources to pull the data, program the reports, and support the additional system hits. Much of it will be very implementation specific and might need to be designed into the system when it is developed. Computer usage hits might tell you a symptom but not the root cause.