After some more testing I think I finally found some settings I'm happy with.
The two settings that made the biggest difference.
1) Dropping the AA from 8x wide tent to 4x wide tent.
2) Reducing the number of visual cars from 36 to 24.
I gained at least 20 fps with each setting and they didn't make that much of a visual difference.
I was able to maintain above 70fps with 36 cars at Monza with all the settings in GTR2 maxed except for the # of visual cars. I even had enough spare frames to turn on trackside objects.
AA = 4x wide-tent
Adaptive AA = Quality
AF = 16x
Texture preference = High Quality
MipMap Detail = High Quality
Catalyst A.I. = High
I appreciate the help and input guys. I was starting to wonder if I should have stuck with nVidia and tried something different but with some experimenting and help from you fine Gents I think I made the right choice.