The question I have is, what would be the proper date to use?

Let's say I pick the date of when the single is released.  I can think of a couple instances when a single did nothing for a year or two and then took off on the charts.  Some tracks I need to add dates for I don't think were released as singles anyways, so I'm guessing I could pick the album release date for those.  I don't think I'd want to pick the album date for every track though, since some tracks are strictly singles until they were anthologized much later. I'm pretty sure I don't want when the song was recorded since a song can sit in the vault for years without a release, plus that info isn't always easy to research.

Ultimately I want to break this random collection of my favorite songs down by decades... maybe even years.  I want to be able to break it into a couple 16Gig collections so I can ultimately use a semi-random selection of the songs in a portable player that isn't capable of storing everything at once. I was thinking of genres, but 90% of it can probably just be classified as "rock" or "pop" so that's not super useful unless you get into more picky labels like new wave/heavy metal/punk and even then, there are enough edge cases to drive one nutty. I'm thinking if I can grab them by year I can more easily split it in thirds, by grabbing 1940-1970 and then 1970-1985 and the 1985-present depending on where the 16 gig boundaries end up. Or even just skip around and grab 1970 then 1974 then 1978 until I reach a boundary. I didn't want to do it by performer names, because that would lump a bunch of the same groups together (tons of Aerosmith, no ZZ Top on a single chip).

any thoughts?  I should just randomly shuffle the collection up and fit as much as I can on a chip at a time anyways... but in the long term I still want to determine how many songs I like are from a particular decade and other geeky stuff, so assigning a date to a song seems like something I'd like to ultimately do.

It all depends on how you look at the song.  A song like 'Iko Iko' by The Belle Stars for example:  It was originally a UK hit in 1983, but never made noise in North America until 1989 (long after the group had parted ways) when it was re-relased for the film 'Rain Man'.

'Dancing in Heaven' by Q-Feel bubbled under the US Hot 100 chart in 1983, but a re-release sent it into the US Hot 100 in 1989. 

'I Go to Extremes' by Billy Joel was recorded and released on the 1989 album 'Storm Front', but it never became a Top 40 hit until 1990.  In 1990, it was a single, in 1989 it was just an album track.

Whenever I make CD compilations, I usually go by when the song charted.  In 1989, 'I Go to Extremes' may not have been heard on the radio, but in 1990, it was in heavy rotation.

I usually like to assign a song to the year when it was popular.

For example, The Mama and the Papa's 'California Dreamin' song was released in late 1965, but didn't really become popular until 1966. So it's more of a 1966 song in my eyes.

Another example is Linkin Park's 'In The End' song which started to get airplay in late 2001, but didn't become a huge hit until about January or February of 2002, so in my perspective it's more of a early 2002 song.

People usually categorize songs either into the year the single was released, the year the song was released on the radio (this date is harder to find and usually gets forgotten years later), or the year the song became popular! I prefer the year the song became popular.

-Good luck-

The question I have is, what would be the proper date to use?


Songs: When released.
Songs as part of a movie soundtrack: When the soundtrack was released, with ID3 tags reflecting "XYZ Soundtrack" as the name of the "Album".
Songs as part of a compilation CD: When the song was released, unless there's evidence that the version that appears on the compilation was unique to the compilation.

As for the grey area of songs that were released in one year but appeared in movie soundtracks (or on charts) in a different year:  Two copies of the song on the disc, each dated appropriately. 

Does it matter to me that Spencer Davis Group recorded Gimme Some Lovin in 1966, charted in 1966 and 1967, and appeared 20 years later on the soundtrack to the 1986 movie Iron Eagle?  No, because diskspace is cheap.