Good question.
A couple of weeks ago, Andy Serling and Tom Amos were talking about the differences between a 9 furlong race at Toga as opposed to Belmont, 1 turn vs 2 turns. Another topic Andy has talked about a lot is turn backs.
We should start a thread in the Handicapper's Corner and talk about this topic, and one about surface. I remember someone posting about surface handicapping a while ago - maybe a search here for "surface handicapping" will turn up something....good topics!
I will use my db to check things out, as best I can, and I am sure others will join in.