I'm not entirely sure which AFCAD you're using, but as much as KLAS is an international airport, real world speaking, they on occasion rarely get anything heavier than a B767. Those generally come from Delta, which means they are headed to the D gates. The occasional B753 from DAL/NWA and COA will come in, and all three of them are at the D gates.
With that said, PIA, VIR, and KAL are pretty much the ones that come in with heavier jets (A340, B744, and B772 respectively), and they all go to the International Terminal (terminal 2). So depending on how close to the real world the AFCAD you are using is, there is where you'll find the heavy gates.
BL.