If this winter has taught us anything, it's have a back-up plan. If the weather is uncooperative (no snow, too much snow, too warm, too cold - I think we've seen it all), it's nice to have alternate activities for your family. Indoor waterparks can be a safe bet and aren't affected by weather like other winter activities can be. In that spirit, here are some US ski resorts with on-site or nearby indoor waterparks.