Of course Democrats should go on Fox - not only, as Suderman says, because candidates often benefit from facing off with antagonistic interviewers, but because boycotting Fox means boycotting the future. Media outlets of all stripes, I suspect, are only going to grow more opinionated/biased over the next few decades, which means that more and more viewers who aren't partisans will, by default if not by choice, end up getting their news from anchors and writers who are. Which means, in turn, that if you boycott a network because it's hostile to your party, you'll be effectively boycotting a host of viewers who aren't.
Save your eyes. Take breaks.