Road Atlanta my favorite by far.
After that in no special order: (I've had a fortunate life)
Mosport, Watkins Glen, Road America, VIR, Laguna Seca, Lime Rock, Pitt Race, Barber, Mid-Ohio
Each is special in its own way. Notice I like big tracks with grass on both sides of the pavement.
And areas of the country that are great to visit. (Food, scenery,History, museums, etc)
Second tier:
Roebling Road, Sebring, Daytona (afterall I am a SEDIV guy)
Third tier:
CMP, New Jersey, Topeka, Thompson
Didn't get to do Indy... 
Since Mrs Frog is always along: It needs to be a "complete experience"... Dining favorites:
Lime Rock: Woodland or When Pigs fly
Road America: Siebkins
Laguna Seca: Nepthe Inn
Roebing Road: Girls - The Pink House Guys - The Shrimp House
Watkins Glen: Lunch - Village Marina Bar - Seneca Lodge Dining - Red Newt