+1 to the store changing rooms - especially in France - was shooping with my wife in Paris in a couple of the big, cheap clothing stores and saw women trying on bras through gaps in the curtain.
Music festivals - most of them have showers and some are mixed (such as Glastonbury) but didn't want to risk it as I probably would have got a stiffy, but they always have standing taps and water troughs where you can wash. I saw lots of girls get topless at these - even brushed a bare boob with my arm when reaching for the communial soap (this WAS an accident!!!). I would go round the camp checking out all the washing ststions, sometimes washing 6 or 7 times. Ince it gets busier, you get the chance to spend time in line watching as well.
Get backstage at some sort of event - I used to play in bands and a few of them had girl members. Always guaranteed some good views backstage. Had more than one converation with a half naked female bandmate about songs and keys etc just before a show. Even more fun when sharing the bill with other bands with girls in them - until you get into the"superstar" league, lots of communial changing rooms. Have recently done a couple of gigs accompanying a "Burlesque" artist and the best part of the show happens backstage, I promide you - especially the girls that just strip down to nipple pasties. They aren't so shy backstage.
Lastly, one I haven't tried yet, get a job helping out an amateur dramatic society backstage - scene shifting/stagehand etc. A lot of these acressses end up changing behind the scenery between scenes instead of going all the way back to the dressing room and sometmes, the dressing room is just an open plan room behind the stage with a few coat racks. A lotof actresses - even amateurs - aren't shy backstage
