Here is what Dharma Master Thich Thien Tam said on Buddha-name recitation as a meditative practice. This is from the Chinese style of Pure Land, by the way.
31) The Four Types of Samadhi
When Pure Land practitioners reach the highest stage, they all attain one state, called the Buddha Recitation Samadhi. This is the realm of all-illuminating still-emptiness, where deluded consciousness has disappeared and only the practitioner's mind continues to dwell on the auspicious features or the sacred name of Amitabha Buddha. However, although the mind is said to "dwell," it is really "non-dwelling," because sounds, forms and marks are illusory by their very nature -- they are really empty.
What are the marks of this samadhi? According to Elder Master Liu Yu, when the practitioner assiduously recites the Buddha's name with one-pointedness of mind, oblivious to body, mind and the external world, transcending time and space, and when he has exerted the utmost effort and reached the goal, right in the midst of present thought, worldly delusions suddenly disappear -- the mind experiences sudden Awakening, attaining the realm of "No-Thought, no No-Thought." That realm is like empty space, all clouds have dissipated, the sky is all blue, reciting is not reciting, not reciting is reciting, not seeing and knowing is truly seeing and knowing -- to see and to know is to stray towards worldly dusts. At this stage, the silver water and green mountains are all Ultimate Truth, the babbling brooks and singing birds all express the wonderful Dharma. The light of the Mind encompasses ten thousand phenomena but does not dwell on any single dharma, still-but-illuminating, illuminating-but-still, existing and lost at the same time -- all is perfect.
The realm of samadhi is, in general, as just described. It is difficult to express in words, and only when we attain it do we experience it. Buddha Recitation Samadhi is always the same state. However, the ancients distinguished four variants, based on the sutras and on different ways of cultivation. These variants are described below.
1. Pratyutpanna Samadhi
When practicing this samadhi, the cultivator has three powers to assist him: the power of Amitabha Buddha, the power of the samadhi and the power of his own virtues.
The unit of practice of this samadhi should be ninety days. In that span of time, day and night the practitioner just stands or walks around, visualizing Amitabha Buddha appearing as a body standing on the practitioner's crown, replete with the thirty-two auspicious marks and the eighty beautiful characteristics. He may also recite Amitabha Buddha's name continuously, while constantly visualizing Him. When practice is perfected, the cultivator, in samadhi, can see Amitabha Buddha and the Buddhas of the ten directions standing in front of him, praising and encouraging him.
Pratyutpanna is also called the "Constantly Walking Samadhi." As the practitioner walks, each step, each word is inseparable from the name of Amitabha Buddha. His body, speech and mind are always practicing Buddha Recitation without interruption, like a continuous flow of water.
This method brings very lofty benefits, but only those of high capacity have the endurance to practice it. Those of limited or moderate capacities or lacking in energy cannot pursue this difficult practice.
2. Single Practice Samadhi
"Single Practice" means specializing in one practice. When cultivating this samadhi, the practitioner customarily sits and concentrates either on visualizing Amitabha Buddha or on reciting His name. Although he actually cultivates only one practice, in effect, he achieves proficiency in all other practices; consequently Single Practice is also called "Perfect Practice."
This samadhi, as well as the following two samadhis, can be put into practice by people of all capacities.
3. Lotus Blossom Samadhi
This is one of sixteen samadhis explained in Chapter 24 of the Lotus ("Dharma Blossom") Sutra. According to the T'ien T'ai School, the "three truths" (emptiness, conditional existence, the Middle Way) perfectly fused, are "Dharma," while the Expedient and the True, being non-dual, are "blossoms." For example, when the petals (the Expedient) of the lotus blossom are not yet opened, its seeds (the True) are already formed: the seeds and the petals exist simultaneously. Thus, in a single flower, the full meaning of the True and the Expedient is exemplified.
In Pure Land terminology, we would say, "recitation is Buddha," "form is Mind," and one utterance of the Buddha's name includes the "three truths," encompassing the True and the Expedient. If we recite the Buddha's name while understanding this principle, we are practicing the Lotus Blossom Samadhi. In cultivating this samadhi, the practitioner alternates between sitting and walking while visualizing Amitabha Buddha or reciting His name, to the point where he enters samadhi. This technique is somewhat easier than the Single Practice Samadhi described above.
4. Following One's Inclinations Samadhi
With this technique, we walk or stand, lie down or sit up as we wish, constantly focusing our thoughts and never abandoning the sacred name of Amitabha Buddha, attaining samadhi in the process. This practice is also called "Flowing Water Buddha Recitation." It is like water continuously flowing in a river; if it encounters an obstacle such as a rock or a tree, it simply bounces back and continues to flow around it.
Normally, the practitioner of this method, early each morning, bows forty-eight times to Amitabha Buddha, and seven times each to the Bodhisattva Avalokitesvara, the Bodhisattva Mahasthamaprapta and the Ocean-Wide Assembly. He then kneels down to seek repentance. From then on until nightfall, whether walking, standing, Lying down, or sitting up, he recites the Buddha's name, either fingering the rosary or simply reciting. Before going to bed, he bows once more to Buddha Amitabha and dedicates the merits of the whole day's practice toward rebirth in the Pure Land. If he is distracted during practice, he should resume recitation as soon as the circumstances of the distraction have passed.
This method is flexible and easy, but the cultivator should minimize distracting conditions and have a good deal of perseverance.
The above is from a very helpful book and should be required reading for Pure Land Buddhists: Buddhism of Wisdom & Faith: Pure Land Principles and Practice