Buck, if this is for the once a year trip, then I would tell you to rent unless of course, you want ot buy something. Are you saying you want just one ski or are you looking for a a second pair to accomapny the hard snow ski? In my opinion, you only need two skis; one with a 66-68mm waiste and then something around 78-84. Skis like the Supershape, Rx8 will handle anything up tp boot high powder and some crud. If its' wet mashed paotoatoes and then I break out my 82's and blast on through. Skiing crud and slop is skill oriented as well so the ski will help only to some degree.
so here's my summary based on assumptions- note I don't know your skill level, speed is irrelevant.
1-ski, hmm, not a fan of a one-ski quiver but rx-8 or Supershape in a 170. Rent skis if you have real powder over a foot or real mashed or slop. If you must, then I would look at Elan Magfire 10 instead, a Head IM72, Atomic Metron M11/b5,Volkl AC3, Hot rod or Nitro
2 quiver- much better- Supershape or Rx8. Best two skis on the market. Then, Head 82, AC3/4, Elan 666,hot rod nitrous, Rossi B3, Atomic Sweet daddy-