Aruba's beaches, and there are plenty of them, rank among the cleanest, widest, and most attractive of the Caribbean. The beaches are all public and access is easy; either through a hotel or by parking directly at the beach. Public nudity of any kind is illegal and insulting to the Aruban people. However, there are many very secluded small beaches along the northeast coast, some requiring a 4 wheel drive vehicle to reach, where you may be alone and do as you wish, subject to interruption at any time by 4-WD or horseback tours. There are no facilities of any kind nearby and the surf is extremly rough and dangerous for swimming. Topless sunbathing and swimming is not against the law, and tolerated on most beaches in the resort areas, but not on resort grounds!!!
Observed some topless at Malmok Beach I just stayed in Aruba Palm Beach area and don't recall any issues with thongs on the beach or poolside despite the "family" area. As for topless, I had read online somewhere that public nudity is not as accepted in Aruba as it is in other Caribbean islands. The recommendation was that it would probably be acceptable on more secluded beaches away from public areas. I guess you would have to check with the "authority" for your particular property's beach or just go with the caveat, "do as other's do"!
First trip to Aruba! Is topless tanning acceptable on any of the beaches? I have seen less of it in Aruba in recent years.
When we were at the Riu two women were topless by the pool but it is not common. There are very few topless bathers at any beach. I'm not certain, but it could be that the beaches are public and not the property of the hotel. Actually it is illegal in most Caribbean countries to go topless in any situation. Aruba included.