Hm... most of the young (under 25) geeks I know don't drink coffee at all. In college, it was beastly caffeinated concoctions involving Mountain Dew (The worst, of course, was Dew-Tang, which involves mountain dew, tang powder, and no water. Don't eat the foam, it will burn a hole in your stomach lining. But if you're pulling an all-weeker, it's the only way.) and the like. Now, in the first job, it's generally either tea or coke. Though many of them are overcoming their coffee-hurts-my-tummy biases and starting to drink it a little bit, I don't know any budding gourmets yet.
I don't like coffee: it hurts my tummy and makes me have to poo. Icky.
I can't stand soft drinks in the morning, or really in the afternoon... I'll have one as a snack sometimes.
I drink tea if I need something warm. As a drastic measure I'll put some of the abysmal coffee from the coffee machine into the abysmal hot chocolate from the coffee machine, and drink that grumpily, and then chew an entire pack of gum to get rid of the coffee breath...
But mostly, I drink water. I have a huge refill mug from a... an eatery I used to frequent (Nick Tahou's Hots, Home of the Garbage Plate, 2260 Lyell Ave. Rochester NY, to read the text off the side) that holds about 40 oz. of liquid. I fill it up with water and ice and play a game: How many times can I empty it in one day?
This is the only way I get to leave my desk, ever-- to refill the mug and empty myself.
It gets me exercise and gives my kidneys a workout. Never had better skin, either. And it's impossible to be sleepy when you always have to pee.