If you plan to watch on a broadcast network, NBC and PBS are devoting two full hours to President Obama’s address and the political reactions, while ABC, CBS and Fox are scheduled for 90 minutes, and the CW a mere hour. On CNN, Fox News and MSNBC, there will be lots and lots of post-speech analysis – and switching among them, like switching among the broadcast networks, often is the most entertaining, if not informative, way to go.