Now that I've gotten some 5.8s under my lead belt . . . .
Two Must Do routes:
Annie Oh! Move for move, p2 gets my vote for the best climbing at the grade so far. Starts off easy, then throws a puzzle at you, then a few moves to very different puzzle, then several more feet to something still harder... one harder and more interesting spot after another to an amazingly sweet crux-exit move. One of the few climbs that made me whoop when I finished it! And I didn't find the gear on p2 particularly worrisome. P1 is another matter, very runout at the bottom and still a little sparse where it gets harder towards the top; might be better off doing p1 of Three Doves or Limelight to avoid 5.5ish R-X climbing.
Modern Times. I think it's the High Exposure of the 5.8s: other climbs may have more consistent moves at the grade, but the crux is tremendously committing and tremendously exposed. The sustained overhangs force a balance between being deliberate enough not to blow the move and the urge to power through before pumping out. Certainly provides a well-deserved feeling of accomplishment as you catch your breath on top! And if the leader falls, it should be all air on good gear. (And if the second falls, it's time to break out the prussiks!) I think most people would say it's a must-do that's also a testpiece.