Not sure there were any tracks I really 'hated', but the loss of tracks from previous games is one of the let downs in GT5.

Surely with all the track layouts already made, it would have been possible with little work to convert them for GT5.
I've just been going through some of the old tracks on Youtube.
I missed Seattle and a Tokyo night course (Special stage Route 11, one of my favourites) before I looked, but looking through the previous game tracks there are tracks that I didn't realise I missed.
I liked the Cathedral Rocks and Smokey Mountain tracks for the transition from gravel to tarmac, and would have been a good chance to run some of the rally cars. The rally tracks that are in GT5 are not too good imho, and rally tracks are not integrated well into GT5. Loads of rally cars, but not many opertunities to use them.
The Complex String with so many different corners would have been interesting.
Lots of city courses missing, Citta di Aria, Costa di Amalfi, Hong Kong, Paris, New York and Seoul.