The results of a thorough thermoelectric characterization, performed both in a vacuum chamber and at atmospheric pressure, of ultra-low-power hotplates based on suspended structures with different layouts are presented in this work and compared with thermoelectric 2D and thermal 3D finite elements simulations. Electrical and thermal properties of the thin films used in the devices have been also measured, involving appropriate on-chip test structures, and their values were employed in both 2D and 3D model. Temperature vs. heating power experimental curves showed the great influence of conduction through air on power consumption and an excellent agreement with the simulated results.