Strictly speaking, its much better for energy (throughout the day) if you stay away from coffee and manage your blood glucose level better (by planning a diet around glycemic indices). This is where energy and awakeness comes from.
Your liver can store about 8% of its total weight as glycogen. This is the ONLY glycogen in the body which can be made available to other tissues (such as the brain). Glycogen is a long chain polymer of glucose, and it is our body's way of storing glucose (it is analogous to starch in plants). The muscles do store about 2% of their weight as glycogen, but this is only available to the muscles themselves.
Taking the average weight of a human liver (1.2kg) and multplying that by 8 percent gives a value of 96grams of glycogen. In a 6-12 hour fast, depending on your last meal and metabolism--this ENTIRE glycogen store is depleted.
Your body can make other forms of energy available to the brain (such as ketone bodies)--but your brain prefers glucose, and these "other" types of molecules generally come from the breakdown of needed tissues, and they contribute to blood toxicity--look up ketoacidosis: a condition which used to be common among diabetics due to their bodies inability to use glucose, their body eats itself and supplies energy that way. Going without food for about 6 hours will expose you to this chemical mechanism, even if its not enough to induce ketoacidosis--it is not good for you. Your brain is responsible for up to 50% of the energy calorie usage in your body, it is a monster which must be fed.
Caffeine tricks your body into a state where you feel more awake, but ultimately you will end up more tired later in the day. You may not notice this, strictly speaking, because as the day goes along you are more equilibrated to the awake state--and we're really good at tricking ourselves into "feeling" awake. It is in the morning, when this equilibration has not yet occurred that we are most susceptible to feeling tired.
If you go with coffee in the morning, make sure you EAT as well. Your brain will thank you, even if you can't tell the difference :)