Great tool/technique for eliminating certain background noises and sounds is spectral cleanup. It does require manual work, but you can "repair" your audio in a visual intuitive way. In my opinion this is one of the best (but certainly not the fastest) way to get clean audio.
To get an idea what I'm talking about take a look at that:http://tv.adobe.com/watch/learn-audition-cc/using-the-spectral-frequency...
Using that in conjunction with gates, compressors, EQs and noise reduction filters this can really do the magic for otherwise unusable audio recordings.
But having clean audio in the first place is always the best solution. ;)