I prefer the 4-volume Liturgy of the Hours edition which has a 4-week Psalter (all 150 Psalms) and a diverse collection of writings of the saints.
The Benedictine Breviary has a one-week Psalter (a small selection of the 150 Psalms) and a less diverse collection of writings of the saints because it emphasizes Benedictine writings. I should think that this would quickly become repetitive!
I find that the 4-volume edition is as flexible as I want it to be. It contains the Invitatory, Office of Readings, Morning Prayer, Evening Prayer, Night Prayer, and 3 Mid-Day Prayers. The 3 mid-day prayers are mostly the same – only the reading and the closing prayer differ from one another (but of course, it all varies from day to day).
I usually leave out the 3 mid-day prayers. Also, rather than do a little more page turning as I carefully follow the annual guide, I typically just go right through it. As a result, I simply do the standard day readings and I miss the readings of the saint or feast day that the calendar would have had me read. In this way, I never really use the annual guide. If I choose, I suppose I could skip the Invitatory and the Office of Readings. In this way, I can adopt a shorter daily prayer devotion in any manner I wish. Why should I leave it in the hands of someone else to shorten the Divine Office in a manner that suits them but not me? The market seems to be filled with prayer devotions, shorter morning and evening prayer books, etc. Why not get the REAL THING (the full 4-volume edition which everyone tries to copy or improve upon, but cannot!), then shorten it yourself in some manner that suits you, if that is your wish?
Please note: I do not want to encourage you (or anyone else) to shorten the Divine Office. I am looking forward to my imminent retirement when I hope to follow the Divine Office more fully and more assiduously. In the meantime, I will continue to avoid the many shorter prayer devotional books and stick to the real thing (even if, in my weakness, I shorten it in some fashion).
P.S. I recommend the black leatherbound edition which has the look and feel of something sacred. The vinyl edition in 4 different colors has the look and feel of something comical.
4-Volume Edition:
amazon.com/Liturgy-of-the-Hours/dp/0899424112/ref=ed_oe_o/102-9770619-9698523?ie=UTF8&qid=1186467062&sr=1-1
Annual Guide:
amazon.com/Liturgy-Hours-Guide-Chrys-Rudnik/dp/0899424570/ref=sr_1_1/102-9770619-9698523?ie=UTF8&s=books&qid=1186467869&sr=1-1