Nothing at this point matters all that much. You're at the end of your window for most adaptations to carry over, so there's no clearly right answer. Did 17 miles leave you really flat? How fast are you hoping to run the half (ie, are you fast enough that your race pace is WAY faster than your long run pace?).
I would cut the distance of the long run slightly and ensure that it's both at a decent pace and that you can recover well. Maybe 14 miles as moderate progression.
As for workouts, don't make them too hard at this point. They can be fast, but cut the volume. The main goal is to ensure that you go into the race fresh and that you avoid de-training. You can maintain your adaptations with less volume in your workouts than it took to get the adaptations in the first place.
Taper training is more art than science. It's highly individualized, and it's as much about making sure you FEEL ready to go as it is about actually doing things to your physiology.