You might be more comfortable running this workout on the roads rather than at a track. You might say that these midweek workouts are like a sandwich. Two relatively easy days on the outside with a relatively harder day on the inside. Don't stay out too late tonight. You still want to catch up on any sleep you might have lost during the hard weeks of training and, especially, before the marathon, when nervousness might have prevented you from sleeping deeply.
Sleep loss is cumulative, and it's time to catch up.
Begin by jogging 10 minutes, accelerate gradually to marathon pace for a 15-minute period, then slide off the pace the last 10 minutes of the run. Keeping with the spirit of this second tapering week, whatever you do today should not be done with high intensity. You're still wounded from all the effort you put into the marathon two weeks ago. Regardless, don't injure yourself by doing something foolish. The top optional end of today's training is an hour of running, as was the case last Saturday and will be the case next Saturday.