I'd agree that classical thump is tricky, it uses loads of variations on the double thump technique which all have to be learnt individually... i'm getting there- slowly! Norweigian Wood isn't as hard as many people think, the tapping sits very nicely under your hands and if you're used to tapping sus2 chords (root, fifth, ninth, tenth) with two hands it's fairly easy for the tune. The beginning has a really tricky double thumb pattern though. Cherokee (Indian Love Song) I've found is Wooten's hardest- i just can't get it. Adam Nietti is also very difficult, first you have to learn how to sweep, which isn't that easy, and then the patterns he uses are tricky too. Dream Theater is definitely hard... try the fast ending to the interlude bit in Metropolis Part 1 in unison with a (very good) guitarist and you'll see. Donna Lee is certainly a great work out. The hardest things I've tried to do are playing Rush lines while singing, the lines themselves are hard to learn, especially to make them work properly, but I dont have the musical ability to sing and play such a part. Actually some really technical death metal is often a pain to learn, check out anything by Erlend Caspersen, he's got it sorted (i most definitely haven't).
But yeah, whatever that guy said earlier about the next song being the hardest is good advice.
But yeah, whatever that guy said earlier about the next song being the hardest is good advice.