First off, Yoda was essential - especially the way they talked about him in the OT, the same goes for Bail Organa. Places like the Jedi Temple and the Senate were either mentioned or alluded to, or were good ideas. Some aspects of the PT were really fantastic (the senate, the jedi council and the temple, naboo (not the gungans, but the main idea behind the planet and the two worlds in one, and the architecture... it was fantastic), Mustafar and Coruscant (which were meant to be the setting of ROTJ (Coruscant's core led way to the development of Mustafar), Felucia (so good that even James Cameron stole it!) and even Kashyyk - hell even the "chosen one" subplot wasn't bad, they just milked it too much and it should've been a kind of subtle plot not this whole "vergeance in the force" bullshit.

Don't get me wrong, there are a LOT of issues with the PT (Qui-Gon's existence, Anakin being "too old" was bullshit - he was the right age but OBI-WAN was supposed to be too old, Yoda was meant to train Obi-Wan, the Clone Wars was barely addressed, the Dark Times were not even addressed, Anakin was a whiny little brat, when he seems like he would have been the Jedi equivalent to a preppy, goodie-two-shoes know-it-all kid at a boarding school who unexpectedly turned to the dark side, the idea of the midichlorians, Jar-Jar and the Gungans, the whole Kamino/Clone conspiracy crap, the over use of CGI, etc etc) - even with all that terrible stuff, it would be ignorant and foolish to deny the good things that also came with the PT (however few it may be to you).