Hi John,
I think as you can see in this thread (and elsewhere), two rules of thumb are that commuters are often eager to add a little distance to a commute to make it safer, but they are sometimes willing to add a big distance to make it more scenic (i.e. go for a nice long bike ride).
I'm probably in the minority in that my safest route is the shortest possible route. I do for about 1mi take a residential street instead of an artery, but (a) the artery is plenty safe: straight with wide bike lanes, and (b) it's just different ways around a rectangle, same distance.
Unlike FB (and others) I take the same route every day, 5.5mi each way. It doesn't become a grind for me because I'm always occupied by the pile of podcasts that I'm listening through.