If Vegas is part of your vacation plans, you could score a DC-9 and 727 if you route via STL.

NW operates all three versions of the -9s into STL from all three hubs and you can then take Champion from STL-LAS on the 727 for a pretty reasonable fare (but only a couple of days per week). You can then work your LAS-KOA flights out to get the 732.

By doing this you could also arrange a day or two to spend in Vegas before continuing on.