I am going to have to say the summer of 83 for me. That summer I saw Return of the Jedi, Vacation and Superman III plus all the the Raiders of the Lost Ark I could stand on VHS.
Summer of '69. That's the summer I got my first real 6-string... bought it at the 5 and dime... Must have played it till my fingers bled.
Wait, no. Damn 80's music. I don't think I had a favorite summer back then. Most were spent at the amusement park playing video games and munchin on funnel cakes.