Lenten Midweek Series & The Church's Lectionary
Since there is a Divine Service with full propers appointed for everyday in Lent (all included in Daily Divine Service Book of, course), a variety of Lenten midweek series present themselves whether your parish observes additional Divine Services or prayer offices.
Your use of the resources in DDSB will, no doubt, be dictated by your parish's custom when it comes to observing Lent. Do you have daily mass or just an additional Vespers on Wednesday or something in between (see poll)?
If you have daily mass, then DDSB obviously has what you are looking for. But if you have what I might deem the Traditional Midwestern Lent with a prayer office on Wednesday evenings, you are not doomed to use some canned series made up by who knows who on the shapes of cross or Valleys of Lent (I am not making that up) or pretending to be a different character each week (You are not a good actor. Yes, I mean you). The daily Lenten devotion of the Western Church, as indicated by the masses appointed for those days, can still guide your preaching and teaching during Lent.
Consider one of the following. (I'm assuming that you will, in any case, use the readings for mass for Ash Wednesday even if you have only Vespers that day - thus, you are looking for five readings appropriate for Lenten Vespers.)
* There is a striking emphasis on the Old Testament in the daily masses of Lent - very nearly every Epistle lesson is from the OT. It would take many a 5-week Lenten Midweek series to preach through all of them and draw Christ from every page.
* In a similar fashion you might use the readings from the Easter Vigil (again, all from the OT), one or two per week on the Wednesdays in Lent. This is especially worthwhile if this is your first year with the Easter Vigil as it will draw the people's attention toward that service.
* Ember Day readings. The three Ember Days in Lent (Wednesday, Friday, and Saturday in Invocabit) have 12 readings assigned between the three of them and present the lentiest kernel of the Lenten theme of repentance and prayer. You could use one, two, or three of those readings at each of your Lenten Vespers.
* For each week in Lent, choose one of the Gospels appointed for daily mass from Monday-Saturday and use that at your Wednesday Vespers. Preaching that Gospel as it relates to the previous Sunday's Gospel will be an edifying exercise for you and your people.
You do not have to be adrift during Lent - let the Church's lectionary guide you! And in your own private devotion, even if you don't celebrate daily mass, use the daily mass readings. This has been a fruitful discipline for me for several years now and it really changes your appreciation of the season.