I used to do rocks or mixers in college, but a family friend was pouring Crown one night and I said I was going to get a Coke - he told me if I wanted to drink from his bottle I could drink it neat, rocks, or with a splash of water, but not any kind of cola or mixer. Since then, I've gone neat with either a small chip or a few drops of water to open up the flavors for most hard liquors - at least those that are "decent".
I'll still make a Rusty Nail, whiskey sour, margarita, martini, rum drinks, or other cocktails from time to time, but don't do the cola thing anymore or heavy ice unless the drink calls for it (margarita, for instance).