Volume 1, Book 11, Number 668:
Narrated Mu’adh bin Jabal:
I used to pray the ‘Isha prayer with the Prophet and then go to lead my people in the prayer.
Volume 1, Book 11, Number 669:
Jabir bin ‘Abdullah said, “Mu’adh bin Jabal used to pray with the Prophet and then go to lead his people in prayer Once he led the ‘Isha’ prayer and recited Surat “Al-Baqarah.” Somebody left the prayer and Mu’adh criticized him. The news reached the Prophet and he said to Mu’adh, ‘You are putting the people to trial,’ and repeated it thrice (or said something similar) and ordered him to recite two medium Suras of al-Mufassal*.” (‘Amr said that he had forgotten the names of those Suras).
* Al-Mufassalaat or the Surahs of al-Mufassal are the surahs starting from Surah no. 50 till the end of the Qur’an, i.e. Surah no. 114.
Prophet (SAW) always kept the congregational prayer short, and ordered others to do so as well. Everyone does not have the time and circumstances to enjoy such long qiyaams everyday. But when you’re praying alone, you may lengthen your prayer as much as you want.
Reciting relevantly shorter Surahs in `Ishaa’ prayer is a Sunnah. The Surahs towards the end of the Qur’an (al-Mufassalaat) are easy to memorize as well. :)