Im going to be in the SI for 10 days in July as well, snowboarding trip. Plan on taking 4x5 and lots of film too.
I went on a trip around in summer earlier this year, and shot everything with a 28mm f2.8 and a 50mm f1.4, except the odd shot of distant things (snapshots) with a 135mm.
Its a great place, I'm sure youll enjoy it, Im looking forward to some -6 nights! (although we got -5 here last night!).