Dont know how many people here can relate but the music that makes me almost tear up is often music that reminds me of some specific times or songs that really have a nostalgic, "reminiscing" sound to it...
For example "The One & Only" by Snoop is a song that often gets me sad as fukk when I hear it, altho its a great song. Same with "Juicy" or "It Was A Good Day"...