I admire anyone who can carry a light or white bag. I would dirty one faster than it could come out of it's dust cover (My only white bag has a pen mark on it...despite my efforts to NOT put pens near, around or inside the bag).
#3 is gorgeous, that would be my pick, as I cannot get down with "Carolina Blue". Call me shallow and loyal to my university :). That being said, #4 is my next pick. Because it's your summer bag, it doesn't need to match with everything, and I think it's fun to pick a current *in* pastel.