Apricot Hill has always been a favorite of mine, I find it an excellent track for testing and as has been said one of the few 'original' tracks that could be an actual circuit.
Tsukuba has taken over in GT4 from Apricot Hill for a lot of my testing now, but I still love to use it, I just wish that we had a wet version of it as well, actually I wish we had wet versions of all the tracks.
Overall I have to say that I have always been impressed with the original tracks in the GT series, its one of the things that realy set it apart from a lot of its competitors. I'm also glad that they have redesigned the tracks as the series has developed, most of the changes have been for the better, the only exception being SS11 (obviously not in GT2 or GT4), losing the evil chicane from the original GT version was a big upset for me.
The original circuits on other games such as Forza or Enthusia have some stand out courses, but not the same high level of consistent good design as the GT series has had.
Regards
Scaff