I'm going to have to agree with Kimi. CART doesn't really have the money to be travelling around the world for now, so an attempt should be made to build it up where it is now, and expand later. But to do this, IT IS NECESSARY TO USE SOME LEVEL OF MARKETTING!!! Come on CART! Get a couple commercials out there. Create some hype!
I also agree that a race in Russia has potential, and Flatspot made an excellent point of this. But two races in "St. Petersburg" would be just too confusing...
What about Trois-Riviers? There's a beautiful course there and for many French Canadians, racing is a part of the culture. If you ran the whole series in Quebec you'd sell out every race, I guarantee it.