That's a good point about why he may have chosen Aruba. If you followed the NH case you would realize Aruba had no clear cut evidence of how NH died or her body to prove she was dead. It could have been an accident and they disposed of her body to hide the fact that she was dead. But we are all aware that Joran was not officially charged because they were not sure what to charge him with (sound familiar?)
I don't think Aruba's legal system "totally" discounts circumstantial evidence. I just think they require something more concrete than we do here in the US. That could change in the future if more "Americans" get the bright idea that Aruba is a good place to get rid of a problem or make some money off a traveling companion. jmo
I truly believe that GG had a plan in the beginning, which is why he started purchasing life insurance on his travel companions before this incident. These earlier purchases were a prequel to this event. Either as a potential, "Oh, maybe the right opportunity will come along, and I can off my partner", or, simply as a cover to make it look like it was something he normally did, just so he could commit his crime at a later date. JMO
GG finally decided, after research and hearing about the flawed justice system in Aruba (circumstantial evidence is a no go), that Aruba was his best bet. Which really goes hand in hand with his obsession with the Natalee Holloway case and with his belief that the Aruba justice system would be more "friendly" to his case. Again, JMO.
GG's original plan was unfortunately foiled, however, when he did not find that perfectly private "snorkeling" area. What he found was Baby Beach, which though not a tourist area, was quite liberally inhabited with locals and not that private. Perhaps he had not foreseen that. Maybe this is what then led him to eventually use the rocky beach area as the alleged "snorkeling and drowning" site which was more private, yet not believable by the local authorities and those who knew the area. JMO
Also this search for the perfect site could explain why he returned back to that area of the island the second day, at the same time of day, in order to "check it out"
GG's plan was ultimately foiled again, however, when he found that Robyn had absolutely no desire to go snorkeling. Again, JMO.
IMO, this just further increased the rage that GG held against women.
Plus, he had gone this far, had spent all this money to get what he wanted. He was not about to give up that easily. After all, in his mind, women "owe him something". Especially a woman who allowed him to pay for her trip to Aruba, and then betrayed him with her "I love you" texts back to her lover. How dare her, that would certainly not do, not in GG's self-entitled eyes.
Unfortunately, it did not bid well for Robyn, as she still ended up the victim of GG's rage and aggression against women. Again, JMO.