7. Nidavellirr
This is underground home of the Dwarves and exists on the same planetoid as Asgard. The Dwarves of Nidavellir are know for forging the most powerful weapons in the nine realms including Thor's hammer Mjolnir. The Dwarven weapons are so powerful largely due to the metal ore Uru, found only in Nidavellirr. Thor might travel to Nidavellirr in The Dark World in order to get some new weapons, or to prevent enemies from collecting them.
8. Hel & Niffleheim
Hel is the realm of the dead ruled by Loki's daughter Hela. Niffleheim is the realm of the dishonored dead, also ruled by Hela. Although Hel and Niffleheim are distinct locations, they are considered to be one realm. Niffleheim, like Jotunheim, is a cold, dark place and may have in fact been the original homeworld of the Frost Giants. The Casket of Ancient Winters is said to reproduce the infinite icy cold of Niffleheim. Hela is a very interesting character. She is the Goddess of Death and a giant. Although she is the daughter of Loki, she doesn't obey all of her father's wishes and is primarily concerned with her interests, namely claiming souls. Hela is unlikely to have a major role in The Dark World, but it would be great to see her appear.