I have used 120 film for snapshots. 645 and a one year old's birthday party, with more adults and kids running around then you could shake a stick at. But I used to photograph weddings and business functions with 120, so I had some experience to fall back on.
By the way, after I gave a nice set of colour prints to the one year old (and her parents) I got this really nice thank you note from her thanking me for my "interesting" photographs.
Maybe it was the shot of the sea of shoes left by the front door. Maybe it was the photographs of the babies, in baby carriers, sound asleep on the floor in the quiet hall, interspersed with diaper bags and cases of beer (it was nice and cool there).