The 'climax' to this mix is definitely the Mogwai song. If it's a starry night, there's absolutely no song that will describe the night better. I also added some nostalgia (Beatles, Brand New, Filter) because it fits the theme of summer/friends well. Finished with "Time" because it's probably the most adequate closer to an album like this
01. The Shins - "New Slang" (Oh, Inverted World)
02. Brett Dennen - "Ain't No Reason" (So Much More)
03. Explosions in the Sky - "A Song for our Fathers" (How Strange, Innocence)
04. Of Montreal - "Oslo in the Summertime" (The Sunlandic Twins)
05. Brand New - "Soco Amaretto Lime" (Your Favorite Weapon)
06. Filter - "Take a Picture" - (Title of Record)
07. The Beatles - "In My Life" (Rubber Soul)
08. Radiohead - "Subterranean Homesick Alien (OK Computer)
09. Mogwai - "New Paths to Helicon, Part 1" (Government Commissions)
10. Smashing Pumpkins - "1979" (Mellon Collie and the Infinite Sadness)
11. Zero 7 - "In the Waiting Line" (Simple Things)
12. Pink Floyd - "Time" (Dark Side of the Moon)