The US Cover
"The structures around Harry show evident destruction and in the shadows behind him, we see outlines of other people. On the back cover, spidery hands are outstretched toward Harry. Only when the book is opened does one see a powerful image of He-Who-Must-Not-Be-Named, his glowing red eyes peering out from his hood." [Wikipedia]
Second thing is that both Voldemort & Harry are looking upwards towards a single point of focus & both are trying to catch whatever is in the air…
The dĂ©cor seems to be like the amphitheatre in Book 5 at the Ministry of Magic Department of Mysteries where Sirius was dead.(In fact, is Sirius dead? JK Rowling never confirmed it…)
There are people in cloaks in between the arches… probably Death Eaters. The addition of curtains on both sides also confirms that this is the archway in Book 5.
However, the ruins at the bottom mystify me since as far as I know there were no wooden structures in the amphitheatre… So it might be anywhere.
The US Deluxe Edition Cover
“The U.S. Deluxe Edition features a different cover picture, with Harry and company flying on the back of a dragon above a small village that is nestled in a valley surrounded by mountains.” [Wikipedia]
The UK Adult Cover
“The UK adult cover shows Salazar Slytherin's locket as described in Harry Potter and the Half-Blood Prince: golden with a large engraved serpentine S in green gems.” [Wikipedia]It was quite predictable that Harry would found out more about Slytherin’s locket in the Deathly Hallows… However, the fact that the locket is on the book cover reveals that it may play a very important part in Book 7. Remember that Book 6 had the Half-Blood Prince’s (Snape) potions book on the cover, & it was indeed important.
It may turn out that “R.A.B.” may play a crucial role in the Deathly Hallows that none of us can imagine…
The UK Children Cover
“The UK children's cover depicts Harry, Ron and Hermione apparently falling into a large treasure of silver and gold; the trio appears frightened in the picture. Some creature's (presumably a house-elf) hand grips Harry's right shoulder, and wields a silver sword with a ruby mounted on the hilt with its other hand. The sword matches the description of Godric Gryffindor's sword in Harry Potter and the Chamber of Secrets. The cover spine features a circle inscribed in a triangle with a vertical line bisecting the pair. The meaning of the symbol is uncertain. The front flap depicts Harry's Patronus (a stag) while the back flap shows a snake in a crystal ball.” [Wikipedia]
The first thing that strikes the eye is the treasure. Loads of Galleons, rubies, golden plates & a suit of armour. On the top of the helmet, there seems to be a dragon. Coincidence? It’s a fine guess that dragons will be deeply involved in book 7. This place can either be at Hogwarts or at the Ministry of Magic.(I don’t think it’s Gringotts - although if it is, then the creature may be a goblin)
Harry, Hermione & Ron are all having bewildered looks in their dress robes(since that’s obviously not their normal robes nor Muggle clothes) & appear to be injured.
The creature behind Harry may indeed be Dobby since those huge ears are characteristic of house-elves. It might even be Kreacher, but Dobby would be better guess, coming at Harry’s rescue with Godric Gryffindor’s sword.
All characters appear to have been thrown out of the stone ring. It might be a portal, in which case, the entrance may be in Hogwarts. There’s no doubt that the final showdown will occur at Hogwarts… Is this the place where the horcruxes are hidden?