Although Dormant Thunder was a huge city, and it would probably be interesting to look around, the group's main target was Treblor Forest, and Dormant Thunder was only a stop they would make on the way there.
But Toz at least wanted to find a less suspicious inn and get proper rest before entering the forest. They also needed to visit the local Explorer's Guild branch office. They had read up on the Treblor Forest before they left for Roaring Skies, but there was no feasible way their information could rival the information available at the guild branch located directly next to the forest.
And, with the group's current strength, they wouldn't make the crossing through the forest to reach the seventh level plane on the other side. With Toz's fifth level badge, getting official permission and reaping the rewards of their harvests during their journey through the forest would also be impossible.