What's the best approach to model a DC machine in Simulink?

Simulink's environment in MATLAB is a useful tool to model various electrical circuits. Simulink includes different electrical machine models, but which of them is the best? Is there any model that includes thermal behavior of the machine as well as the electrical behavior?

If we want to create a model from scratch, what resource(s) do you suggest to use? A simple model that provides highly accurate response is desired.