From DIA On American Airlines? International: Non-stop=Zero. Direct=Zero.
Domestic: Non-stop: LAX, ORD, DFW, MIA Direct: ANC, AUS, CLT, DTW, MCI, OKC, LGA, MCO, PIT, DCA.

You may want to try another forum to get a better response to this general question. Other than that, you can try OAG online, but it's not cheap for a subscription.