Cheers!
Most of the time I play fortress mode, focusing on easy, peaceful fortresses where I can experiment and create a lot of engravings/encrustings. Occasionally, I do a bit of exploring in Adventure mode, but this is a minor thing for me.
My first concern about a world is diversity: There should be humans, goblins, elves, and dwarves around (okay, goblin civs, to be precise (^_^;; ). Kobolds are a nice addition, but I do not always check about them.
Actually, this is the most difficult part, as early contact between humans and elves often causes elves to go extinct. In addition, if either of them has too small a heartland to move back into, they will usually get extinct. Similarly, goblins sharing mountain chains with dwarves are at a very high risk of getting wiped out as well (T_T)
Secondly, I need temperate, calm, non-aquifer locations for my fortresses, reachable by all trade partners (unless I am exploring a somewhat different site, like a sweetwater island).
Finally, because I like engravings, I need some large regions (forests, mountains, ...) offering fortress locations and at the same time having exciting histories (like unending conflicts between elves and humans). In order to boost histories, I also like to increase the number of caves (the default values are way too low in my opinion anyway).
Deathworks