When I'm trying to get creative I use the following:

http://www.airlineroutemaps.com
This has almost every airline you might want to see. I like to use the site to see what connections can be made, what airlines fly where, and see where else I might be able to go with stopovers/OJ.

For Oneworld I use this site:
http://onw.innosked.com/?show=MAP

Just because the route exists doesn't mean there are seats :-P The good news is that with 50 days to travel, you should be ok to find seats as long as you are flexible during those 50 days.

Once you've plotted out a route:

www.awardnexus.com

And search for the flights there by date. Allows flexibility in searching by date as well as award class.

I've had good luck using these three in combination, and then calling with exact flight numbers when booking. Agents have told me there is no availability, but when I give them flight numbers, especially on partner airlines, they then have no trouble.