I have miles on UA, USair, and Delta as of now. I know all 3 are part of alliances, but have trouble searching for partner awards.

What is the best FREE way to find partner award travel and book it? Should i sign up for all the other FF accounts and then call the airline? If i do this am i charged the phone booking fee?

Im sure there is a paid service that makes this much easier. So what is the best non free option as well?

Thanks