Chances are you've seen these pics used across multiple of the example IG profiles; definitely the poker card wall and the catch flower wall. If you've got a friend or even just a tripod for your phone you should be able to get some good pics at these spots.
The Catch wall is the entrance to a restaurant in the Aria main lobby, it's inside the tunnel that you see when you first walk in.
The flower bed and hanging ball spot is to the right of the Catch wall and can make for some decent shots but isn't a main attraction.
The Poker Card Wall is just outside the PokerGo! Studio which to get to just walk to the far side of the valet drop off circle.
If you keep going past the card wall and down a giant flight of stairs there is a condo lobby made of all Marble with fancy art and decor; be cool and nobody will bother you there.