"Move the "Fluid" threshold properties to the TileView level.  It seems rediculous that these need to be specified in every Item (sure, I know there is templating, but this would also reduce your code/logic for calculating the areas of items).  If this can be done with attached properties it might be more intuitive and less obtrusive on the control (ex. <RadTileView RadFluidContentControl.LargeToNormalThreshold="200" />)."