I've used Audacity before for quick jobs. Shows that run long 2hrs + seem harder because the songs near the end tend to be more out of sync. Syncing each song or a couple of songs would be the way to go for me for long show recordings. Could be my camera is getting old.
Vegas users can buy a plug in called Excalibur 3.0 to help syncing up audio with video. I mainly tried the demo for it's multiangle use but syncing the audio is as simple as dragging the wav to the desired trim. I haven't tried this yet but sycing the audio to video for a song was very easy. Just match up a point in the video of a cymble crash to it's audio and Excalibur syncs it up. Matching up multiple videos is easy when hunting for a camera flash.
Humph, I really should cough up the C note for this plugin. You can download a working demo and use it for 15 days. Well worth the effort for any vegas users.