The kind of meditation a rosary can engender is precisely the same as that recommended by St. Ephrem the Syrian:
"Come, let us meditate on his sufferings with tears, thinking on fear, meditating with trembling, saying to ourselves, ‘Christ our Saviour for us the impious was given over to death’.
Learn well, brother, what it is you hear: God who is without sin, Son of the Most High, for you was given up.
Open your heart, learn in details His sufferings and say to yourself: God who is without sin today was given up, today was mocked, today was abused, today was struck, today was scourged, today wore a crown of thorns, today was crucified, he, the heavenly Lamb.
Your heart will tremble, your soul will shudder. Shed tears everyday by this meditation on the Master's sufferings. Tears become sweet (for) the soul is enlightened that always meditates on Christ's sufferings."
- "On the Passion"
Other fathers advise it as well.
"[L]et us not merely read of these things, but bear them in our mind; the crown of thorns, the robe, the reed, the blows, the smiting on the cheek, the spittings, the irony. These things, if continually meditated on, are sufficient to take down all anger."
— St. John Chrysostom, Homilies on the Gospel of St. John (Homily 84)
"I have referred to images harmful to the soul because there are other images which are permissable, as St. Kallistos noted. Such images include the contrition, the grief, and the humility of the heart; the meditations upon death, the future judgment, and the eternal punishments; the study and meditation upon creation and the Incarnation of the Lord; the phenomena of creation, the miracles, and the mysteries of the Lord’s Incarnation -- the birth, the baptism, the crucifixion, the burial, the resurrection, and so forth, as we said before. Finally, it is permissible, when fighting against certain inappropriate and evil imaginations presented by the enemy, to use other appropriate and virtuous imaginations. Do not pay any attention to the shameful and fearful images of the foolish and irrational imagination and do not be frightened by them. Ignore them and consider them unworthy of your attention. They are empty playthings without any true substance. He who is used to ignoring the imaginations can also ignore the real things themselves that are depicted in the imaginations, as St. Maximos has noted: “He who conquers over the passionate fantasies will also be ale to prevail over the realities they represent.” Let me conclude this chapter and summarize what I have been saying. Know that if you impress upon the board and chart of your imagination beautiful and appropriate images, you will be praised on the day of judgement, when what each person imagines secretly will be revealed. But if you allow inappropriate and evil images to be recorded and to dwell in your imagination, you will be condemned.”
- St. Nicodemus of the Holy Mountain. (A Handbook of Spiritual Counsel, p. 151)