I think it's great that you can discern such differences. As Reductor says, if you are working out what to do for yourself, you have to just try it and see (since such details are not in the suttas).
If you were following a particular teacher, in person, or via books/internet/etc, I'd try out what they recommend for a while (weeks), and see if what they say is useful for you. That calm and brightness is the sort of thing that Ajahn Brahm or Pa Auk Sayadaw discuss in their meditation instructions. Pa Auk recommends starting with the breath at the nose tip. Ajahn Brahm a general awareness, but they lead to the same place, an eventual focus on a mental conception of the breath.
Ajahn Brahm wrote:The fifth stage is called full sustained attention on the beautiful breath. Often this stage flows naturally and seamlessly from the previous stage. As briefly
discussed in the previous chapter, when one’s full attention rests easily and
continuously on the experience of breathing with nothing interrupting
the even flow of awareness, the breath calms down. It changes from a
coarse, ordinary breath to a very smooth and peaceful “beautiful breath.”
The mind recognizes this beautiful breath and delights in it. It experi-
ences a deepening of contentment. It is happy just to be watching this
beautiful breath, and it does not need to be forced.
This sixth stage is achieved when one lets go of the body, thought, and
the five senses (including the awareness of the breath) so completely that
only a beautiful mental sign, a nimitta, remains.
Mindfulness, Bliss, and Beyond, pages 19 and 21http://ebookbrowse.com/ajahn-brahm-mind ... -d84597124
Pa Auk Sayadaw wrote:To begin meditating, sit in a comfortable position and
try to be aware of the breath as it enters and leaves the
body through the nostrils. You should be able to feel
it either just below the nose or somewhere around the
nostrils. Do not follow the breath into the body or out
of the body, because then you will not be able to perfect
your concentration. Just be aware of the breath at the
most obvious place it brushes against or touches, either
the top of the upper lip or around the nostrils. Then you
will be able to develop and perfect your concentration.
The concept of the breath is the object of mindfulness-of-breathing.
It is this object you must concentrate on to develop concentration.
Just before the nimitta appears, a lot of meditators
encounter difficulties. Mostly they find that the breath
becomes very subtle, and not clear; they may think the
breath has stopped. If this happens, you should keep
your awareness where you last noticed the breath, and
wait for it there.
Knowing and Seeing, Page 21... http://www.buddhanet.net/pdf_file/know-see.pdf
These books may be helpful (or they may make little sense, it depends on your experiences and tendencies...). Other teachers have different interpretations of anapanasati. There is plenty of room for creativity in technique...