This post probably answers my post in your other thread about if you are in south shore the whole time.
Atlantis is newer, both are within spittin' distance of each other and about a 5-10 minute drive from downtown. I don't think you can go wrong with either. The Peppermill Motor Lodge is slated for demolition sometime within the next year or so. Both are more of a locals hangout. Peppermill usually sells descount lift tickets to guests, talk to the concierge.
From either hotel you are 30 minutes to Mt Rose, and about an hour to all Nort Shore Resorts including Sugar Bowl.
Presently skiing is fantastic above 8000 feet, Mt Rose, Heavenly, Kirkwood, Mammoth.