I think what was said above about intl by bases is correct and makes sense.
As far as I know, only certain cities will be in the intl subset, at least that was the intent in TA1. Cities like MEX, SJO, AUA, and MBJ will be included. Easier cities like CUN and SJD will not. There are plenty of guys in Houston who avoid anything intl, but if you threw a little money at it, they would be all over it. The excuse I commonly hear is about increased risk for no extra reward. Of course, these same guys will fly a full 800 into MDW in a blinding snowstorm and ice, but I digress.