Thanks for the clarification on the sills class. I'll just remember to keep that on.
When I insert a door into a wall it will automatically change properties. It will assign it's own color and lineweight if I use the door preferences dialog box. If I don't use the dialog box and just insert the door, it will keep the settings I have in the object properties, but as soon as I flip the swing, change the settings or try to change the class, it automatically changes to it's own lineweight and color. Neither of which are the proterties of the 'sills' class or my door class.
One other question- is there a way I can universally select and change properties of more than one door or window at a time?