Laylatul Qadr 97:1

Hira Cave

{ إِنَّا أَنزَلْنَاهُ فِي لَيْلَةِ ٱلْقَدْرِ }

"We descended it in Laylatul Qadr"
Ibn Arabi
Laylatul Qadr is the physical frame of Muhammad (saaws) in the temporary state (Hal) of the Heart in which he became veiled from the witnessing of the Essence. The descent cannot occur without this state. Qadr is the high rank and nobility of the Prophet (saaws)- the verse means that the high rank of the Prophet does not appear and is not known to himself until that night.
If the fast of Ramadan is started on a Wednesday then Laylatul Qadr is the 29th night.
Fakhr al Deen al Razi
The use of  the "We" pronoun is for the sake of investing the matter with Greatness.
On the meaning of Qadr:
Qadr with a silent ( sukoon) "d" is a verbal noun (masdar) meaning high rank and with a "d" that has a Fatha (da) is a noun meaning :" the decree", " the measuring out" as in Surat al Dukhan 44:4 " On that night every judicious matter is separated distinctly".
The night was called al Qadr (cooking pot) because the Earth becomes overfilled with Angels.
Various Ahadith point to its occurrence in the last 10 days of Ramadan 
al Hassan al Basri
It is the night of the 17th of Ramadan because the day that follows it is the day of the battle of Badr.
Sahl al Tustari
It is named the night of Qadar" measuring out" because during it Allah swt decreed Rahmat ( Divine Mercy) for all his slaves.
Rouzbehan Baqli 
 That night where His Beauty is revealed to the Divine Knowers and the people of Winessing from those who are favored with His proximity. It is He, who has decreed their planes of consciousness (Manazil, pl. of Manzil) in the stations of Knowledge or Unveiling. It is He also who has decreed the ordainment of the Unseen and brought into view the Lights of His Dominion and of His Innermost Realm ( al Jabarut) to those endowed with Hearts. That is why Angels and the Spirit descend on that night, for they give them glad tidings of approaching Union ( Wisal) and eternal revelations of Divine Beauty.

It was said that the descent of the Angels on that night is in order to infuse the heart of the Divine Knowers with Rooh ( Spirit) .

Qushayri

 It is a night during which the worshippers find the measure of their Selves and the Divine Knowers witness the measure of the One they worship....What a difference there is between the finding of a Qadr and the witnessing of a Qadr!