Thanks Kyoshi! I've would have never find this thread!
Personally living in California, my favorite racetracks would be Mazda Raceway Laguna Seca, Thunderhill Raceway, Sears point, Buttonwillow, and Willow springs.
I also love Nurburgring, Tsukuba, VIR, Mid-Ohio, Road Altanta, Sebring, COTA, and Ebisu.
Here is some sick miata action in Laguna Seca during the Mazdas at Laguna Seca 2015!
Thunderhill, home of the longest race course in America!