Hi!
From an aesthetic point of view, I would suggest a multi-tile sweet water island in a lake in the mountains. I always like those island lakes and having a settlement there looks really awesome on the world map. A micro sweet water island would also be interesting.
For something more intriguing, I suggest genning a world with the following:
* Make all variances except for volcanism 100 or less (=> large sub regions)
* Minimize number of uninhabitable terrain (aka oceans, glaciers,...)
* Have history hidden
* Do not cull historic figures
* Run world gen for 2000 years
* Have as many civs and caves as possible (caves should be 400-500 sized)
* Have history displayed fully in fortress mode
Once you have genned the above world, make a fortress at the merging point of at least two large, inhabitated subregions (preferably with ruins in those subregions).
The goal is to do a lot of engraving and decorating in order to see all the historic events. It can be very interesting what you get to notice. In my current fortress, of course there are depictions of the human-elven conflicts raging in the forest I have settled in, but there are also many engravings about black bears fighting with goblins and other civs. And in another fortress, I saw an interesting series of engravings about humans fighting sasquatches.
Engravings are especially good for that, since they give you a hint as to what they are about even before you look at them, so there is this "dokidoki" factor when you see a "C" or "D" or "S" engraved (at least until you notice that you have an engraver who adores donkeys (T_T) ).
Deathworks