Brian - I don't think these are useful when you have to zoom in so far to see them, especially since their name doesn't appear until you are REALLY zoomed in. If I was airborn with a little turbulance trying to find a fix that's roughly 15 miles northeast of the airport, I don't think I could do it as-is. I suggest they be made the same size as obstructions on the Vector chart, and a different color (red?). Also, remove the parenthesis - they're just clutter. To make them user selectable, either add a checkbox under "Obstructions" or if they don't warrant a checkbox of their own you could change "Obstructions" to "Obstructions/Fixes" and then in the flyout window, under "Enable Terrain Alerts" you can add "Enable Fixes". This would make them user-selectable. I personally think I'd turn them on.
Often when I'm inbound VFR to a strange airport, I'll hear "N1234 is at FIXEM inbound on the GPS 12 approach". Of course I have no idea where FIXEM is, and having the option to quickly spot it on the Vector chart would add to my situational awareness.
(And you thought this was going to be EASY!!!)