Friday was probably the easiest day to pick a schedule that is practical and not full of conflicting set times. Starting the day off with The Soft Pack and The Mountain Goats is a no-brainer. If you have to skip The Soft Pack to get a good spot for The Mountain Goats, do it. The band is incredible in a live setting and it should be interesting to see them on a huge stage.
The battle between Miike Snow and Girls is a tough one but I would say that you should go with whichever is more important to you. Miike Snow have great songs and would probably translate really well in the festival setting. Girls make for a more intimate performance but they have some crowd-pleasers in their catalogue that will probably appeal to everyone, even the Greek life kids out there.
The rest of the day is smooth sailing. From The Black Keys to Beach House to Spoon to Sonic Youth to The Strokes, you can't really go wrong. My only question is, why are The Strokes at a higher bill than Sonic Youth? Vampire Weekend is also playing at the same time but if that is a tough decision for you, you're probably better off at Vampire Weekend. The contest isn't a real one though.