The history of the song "Good Night" began back on June 28 1968 with some taped rehearsals. This was a tune written by John Lennon especially for his son Julian who was a small boy at the time. It was decided that Ringo would sing the song and that the running order on the new LP (eventually "The White Album") would end with this track.
During the rehearsals, Paul played some piano and George Martin played a shaker as Ringo sang the tune and an arrangement took place during this time. A snippet of this rehearsal can be heard commercially on the Apple 2-LP/2-CD "Anthology 3" project. This is in mono but it becomes cross-faded into the ending of the orchestral version of the song in stereo.
In the end, five takes were properly recorded with a Ringo vocal overdub completed on July 02 1968 and taken away via an acetate from the studio by George Martin for the "over the top" orchestral overdub which occurred on July 22 1968 in the large Studio 1 at EMI Studios in London.
There are three main mixes available for the tune: the first one is mono with some music edited and some extra 'whispering' vocals at the end of the tune and can be heard on the "Peter Sellers" tape which was an early mix of some of the White Album songs and given as a gift to the actor from Ringo. The main difference between the mono and stereo mixes on the official LP is that the stereo mix has the orchestra fade in at the beginning of the song whereas on the mono mix the orchestra comes in at full volume.
The "Peter Sellers" version can be found on bootleg CD such as "Unsurpassed Masters Vol. 4" and (of course) "The Peter Sellers Tape".