I had been to countless dimensions before, including the upper planes filled with positive energy and Holy Light as well as the distorted and chaotic lower planes. I wouldn't know which plane left me with the deepest impression as a suitable vacation spot, but the most unsuitable plane of all for vacationers or to live in would absolutely have to be the Fire Elemental Plane.
Not only was the air scorching hot, it also contained toxins. Additionally, I was attacked six times after walking around for less than 10 minutes. I was attacked by a tremendous berserk fire demon as well as low-level fire elemental creatures that I could crush quite easily. These monsters would always unhesitatingly attack you the moment that they saw you. The only difference between them was the sound they made when they attacked.