Another neat base RTSer. In RA2, I would place all buildings except base defenses, ore refineries, or land unit production buildings adjacent to my conyard, then build a wall around them. Basically, unless it was vital for a building to have open space in front of it, I would put it into this massive complex around my conyard. Vulnerable to superweapons, yes - however, resistant to ground attack. Also, I did not tolerate the existence of enemy superweapons. They were priority targets for my forces.
In Rise of Nations, I give each city a purpose. My second city will normally focus on mining and knowledge (since it often is built in the second age, when those resources become available). Other cities will focus on military production or resource production.
This is in direct opposition to computer players, who will scatter buildings throughout their nations. On the mini-map, their territories seem crowded. Mine are more open, with everything around a city.
In C&C games, I destroy trees and buildings if I can. I will delay finishing off the computer so I can completely eradicate every object in the city. In one level of C&C3, my building-destruction habits became useful. When you attack Washington DC as Nod, GDI garrison nearly every building on the map. My solution was to use saboteurs to destroy every building between me and the GDI base. It was a long and grueling battle, but it paid off. A long stretch of destroyed buildings marked the path my troops took.
In Half-Life 2, I destroy nearly every destructible object I come across, unless I am pressed for time or in a friendly base. I also use the gravity gun to throw around other objects, creating a sense of carnage. Also, if I have spare ammo, I will fire bullets into walls to create the lambda symbol. And when I used cheat-codes to give me the super gravity gun in earlier levels, I would arrange Combine bodies to make it seem like the latest shooting incident was the result of a homosexual love triangle gone bad, with one soldier finding another two in bed, shooting them both, smashing up the house, then committing suicide.
I also stand next to Alyx as much as possible. If she is sitting on the ground, I crouch next to her. I think this is a result of her character being so well drawn that she evokes emotional response, and my only tool for nonviolent emotional expression is altering my position.
There are advantages to these habits. Clumping buildings in RTSs saves space and makes it easier to defend everything. My city-building habits improve efficiency in RON (since every resource-gathering building is in a city, they all benefit from the city's presence), and again, make defense easier. And in Half-Life 2, I have benefited a few times from my rampant destructive habits. In Episode One, when the elevator gets stuck, I started pulling consoles off of walls out of frustration. Turns out that one of the consoles hid an opening that provided a solution to the puzzle.