What's the main thing you look for when choosing a world to play in?

I tend to pick worlds based on where I'd go on vacation if I had the money and time to do it. Hence Isla Paradiso. It did throw me for a loop when my Sunset Valley game gave me a challenge to learn the diving skill (diving? maybe I'm remembering the wrong word) and apparently you can't learn that in Sunset Valley. I took the class, but that had no effect on my learning or the challenge. IP hilariously bleeding over into SV.