Here are the screenshots from my recently completed park for the Challenge:
First up, here is an overview of the park. It has 35 rides including the two coasters:
http://themeparkreview.com/game_exchange/images/thumb/2515_holiday_park_2011.jpg
Next, we have the Blizzard, a B&M Sitdown Coaster with seven inversions:
http://themeparkreview.com/game_exchange/images/thumb/2516_blizzard.jpg
Finally, we have the Polar Express, a Premier Rides Launched Coaster:
http://themeparkreview.com/game_exchange/images/thumb/2517_polar_express.jpg
Here are the links to the park and tracks in the Game Exchange:
Park: themeparkreview.com/game_exchange/track.php?id=2515
Blizzard: themeparkreview.com/game_exchange/track.php?id=2516
Polar Express: themeparkreview.com/game_exchange/track.php?id=2517