The 2007 Champ Car race at Mont Tremblant is one of my favourite single seater races of all time so I would live Indy Car to return there.
I do not think either series ever raced at Road Atlanta but I have heard about some great races there too.
I think every series should aspire to race on the best circuits available. However as modern F1 is proving the best facility circuits do not mean the best racing circuits.
For the Americas number one open wheel series to not race at Austin (it’s best facility) does seem quite odd but who knows what the F1 contract is.