South City would be too harcore IMO, though so4 could be an option perhaps. Blackwood is probably too short and too narrow for this stuff. Fern Bay has been used this year. Westhill is filled of blind corners and tricky places where you can easily spin the car, not to mention that the laps are rather short... so maybe not a good idea. as4/5/6/r is always good for multiclass racing but it's overused. Kyoto GP Long is mint but has been used back in 2008.
Why not Kyoto National, I rather dislike the track as it looks like a bit Tilke-ish(never liked rovals in fact), but it probably is the safest option out of the non-overused track. That said it'd be shorter than any of the track used in the past 16 hours races.