Welcome to FT.
I don't know of any sites which display FF availability, although I believe that a few of the airlines are starting to add this "self-help" feature to thier websites. This would be an extremely convenient enhancement to the airlines' websites that would also free up their FF agents from having to spend time with customers who are still just planning thier trips but aren't ready to commit yet.
Whenever I need to book a FF award ticket and it is not a simple itinerary or if the trip is a very important one (VACATION!),I visit my local CTO. I have found that the CTO agents are able to spend a bit more time with you than the phone agents. It is just that the phone agents have to handle calls from people all over the country, while the CTO has the luxury of concentrating on customers who are visiting the CTO.
Good luck.