This paper examines various activity estimation techniques in order to determine which are most appropriate for use in the context of field-programmable gate arrays (FPGAs). Specifically, the paper compares how different activity estimation techniques affect the accuracy of FPGA power models and the ability of power-aware FPGA CAD tools to minimize power. After comparing various existing techniques, the most suitable existing techniques are combined with two novel enhancements to create a new activity estimation tool called ACE-2.0. Finally, the new publicly available tool is compared to existing tools to validate the improvements. Using activities estimated by ACE-2.0, the power estimates and power savings were both within 1% of the results obtained using simulated activities.