I spent probably two days searching for a great location to embark from, and when I gave up, I found it. What I had wanted to build, was a chasm that cut across a mountain with a brook on the other side.
For two reasons: My farms could be west of the chasm, by the brook, and my main fortress could be east, across the chasm. I built a drawbridge over the chasm, and then carved parapets into the mountain. All in all, the fortress is looking amazing.
Can't say I agree, as 3D allows for much more strategy. I build what I call "dog pits". In order for an enemy to get into my fortress, they have to travel through three seperate chokepoints. Each chokepoint ends in a stairway leading into a small room that has four war dogs in it I have a lever that seals each hallway. In order to get past all the choke points, the enemy must go down the stairs, meaning no ranged attackers will be able to shoot at my dogs without being in range of their attacks, and the floodgates ensure that I can give my army proper time to respond. The way I have built the chokepoints, ensures that the enemy will only be able to fight my dwarves one at a time, while my dwarves will be able to fight three on one.
Through simple architecture, I am able to keep my fortress safe. Also, the ability to channel water, and move it up and down is quite nice. I created a moat fed by two artificial waterfalls using six stacks of pumps (And fueled by the very water they were moving and a windmill... =/ but we don't speak of that...). All of this couldn't be done with a 2D map. Personally, the amazing feats of engineering are what motivate me to play these types of games.