I used to use the SA toolbar to do my feature to raster conversions but I don't see that available on the toolbar in v10. I've set the environment settings that I need. The resulting raster will not stay within my analysis mask or processing extent. It does snap to my snap raster (all the same GRID: "cnty_bndy") and output the correct cell size. I don't understand why it creates cells for features that extent beyond my analysis mask? I've tried polyline to raster and feature to raster. This isn't very complicated I know.
(There is not an orange cell underneath the darker cell).
Those tools do not honor the Analysis Mask environment setting. Each tool in ArcToolbox has corresponding documentation that will tell you which environments they will honor. For example, the Polyline to Raster tool honors the following settings: Compression, Current Workspace, Output Coordinate System, Extent, Pyramid, Scratch Workspace, Cell Size, Snap Raster.
You can Clip the resulting raster to your mask after the conversion.