I managed to get 100% on Everlong - Foo Fighters, 100% on Misery Business - Paramore, 100% on Beat It - Michael Jackson, 98% Eye of the Tiger - Survivor, 97% on Stranglehold - Ted Nugent (I didn't think that song was ever going to fucking end), and 95% on Sweet Home Alabama - Lynyrd Skynyrd. All were on lead guitar on Hard. While none of those songs are by any means the hardest in the game, they are pretty freaking difficult.
I tried playing The Middle by Jimmy Eat World and Misery Business by Paramore on Expert and failed miserably within the first half of each song. I will get them one day.