I wore skimpy Speedos without a problem at several beaches. There are many Dutch tourists also in skimpy swimwear so should be fine. On the southwest part of the island are a series of small beaches that are amazing
Grote Knip, Kleine Knip and Playa Kalki are all smaller and very beautiful. Mambo beach is bigger with more food and drink options. Also if you want a cool experience, do Substation Curacao which is a submarine for a small number of people that takes you out along the reef.