When we were developing Photosynth, we thought about how people would actually want to use it. Weddings came to mind--a single event that is heavily photographed. And we've found a number of synths that show the added dimension that Photosynth brings to wedding photography:
You can see more by just searching on the word 'wedding'.
Some people probably tried to synth their wedding photos because it was the biggest collection of photos about a single event they had on hand, but not all of them work as synths. Pre-existing collections don't usually turn out as well as photos shot with synthing in mind. If you'd like to synth a wedding, here's a tip: Ask everybody who's brought a digital camera to give you copies of the photos they've taken. Between the photos you'll take (with synthing in mind) and the comprehensive coverage that everybody else's pictures will have of the same places, chances are good you'll have a pretty complete synth. But remember, just because you have 500 photos to work with doesn't mean you need to include all of them in your synth. Use the ones you think will knit together best, and leave out the ones that don't match up to any others.