If you take a hire car, the Summit County towns of Dillon, Silverthorne and Frisco are good options for (relatively) lower cost condo accommodation and easy proximity to Breckenridge, A-Basin (beware the East Wall), Keystone and Copper Mountain. Vail and its expensive, impossibly great back bowls is about another half-hour (or more depending on traffic and road conditions) down the highway over Vail Pass. Try here for openers. If you want to focus more on the kids' skiing, I'd say head for Keystone or Copper. Winter Park is nice but as L-o-M said it's mostly Denver commuters, as is Loveland (which isn't really worth your time).