I'll keep this brief. The Democrats should use the shutdown as an opportunity to promote the fact that the ACA health exchanges have just opened. Basically, every Democrat on TV, from the President on down, should end every interview with something like: "but even though the GOP's done a huge disservice to every American and shut down the government, remember that the health exchanges have still just opened. Sign up if you need health care!"
The Democrats should have a consistent brief blurb about this on EVERY media appearance from today until the shutdown is over. Take something that's hurting Americans and use it to do something good.