I'm a voyeur at heart, and certainly agree with the mall approach. Also consider public park, which are great to lay out in for a picnic. Sitting lower with people walking by affords an opportunity for downblouse, and stretching out the legs in a short or medium length dress will give you good upskirt opportunities. Large do-it-yourself stores are good with big long aisles and an opportunity to lean over looking at lower shelves. Large food stores are good too, with lots of bright lights. The beach or pool of course for skimpy swimsuits, but also consider leaving the curtain open in fitting rooms, the floppy sleevless tshirt at a waterpark, or just laying out in the sun in the yard with a swimsuit top that is too small, or bottoms too big and gap. Also consider going to a nudist resort or beach. Not exactly peaking under clothes, but something worth experiencing. Hope that helps. My little perverted brain may have gone overboard here.