In order to apply different styles for the different type of RadTileViewItems you can use the ItemContainerStyleSelector property of the RadTileView and implement custom style selector. Then you can define Styles for your items and depend on their type you can select the templates.
For your convenience I prepared a sample project that demonstrate such approach. Please give it a try and let me know if it helps.
Check out Telerik Analytics, the service which allows developers to discover app usage patterns, analyze user data, log exceptions, solve problems and profile application performance at run time. Watch the videos
and start improving your app based on facts, not hunches.